A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge. However, in quantum physics, organic chemistry, biochemistry, the term molecule is used less also being applied to polyatomic ions. In the kinetic theory of gases, the term molecule is used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are monatomic molecules. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with oxygen. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are not considered single molecules. Molecules as components of matter are common in organic substances, they make up most of the oceans and atmosphere. However, the majority of familiar solid substances on Earth, including most of the minerals that make up the crust and core of the Earth, contain many chemical bonds, but are not made of identifiable molecules.
No typical molecule can be defined for ionic crystals and covalent crystals, although these are composed of repeating unit cells that extend either in a plane or three-dimensionally. The theme of repeated unit-cellular-structure holds for most condensed phases with metallic bonding, which means that solid metals are not made of molecules. In glasses, atoms may be held together by chemical bonds with no presence of any definable molecule, nor any of the regularity of repeating units that characterizes crystals; the science of molecules is called molecular chemistry or molecular physics, depending on whether the focus is on chemistry or physics. Molecular chemistry deals with the laws governing the interaction between molecules that results in the formation and breakage of chemical bonds, while molecular physics deals with the laws governing their structure and properties. In practice, this distinction is vague. In molecular sciences, a molecule consists of a stable system composed of two or more atoms.
Polyatomic ions may sometimes be usefully thought of as electrically charged molecules. The term unstable molecule is used for reactive species, i.e. short-lived assemblies of electrons and nuclei, such as radicals, molecular ions, Rydberg molecules, transition states, van der Waals complexes, or systems of colliding atoms as in Bose–Einstein condensate. According to Merriam-Webster and the Online Etymology Dictionary, the word "molecule" derives from the Latin "moles" or small unit of mass. Molecule – "extremely minute particle", from French molécule, from New Latin molecula, diminutive of Latin moles "mass, barrier". A vague meaning at first; the definition of the molecule has evolved. Earlier definitions were less precise, defining molecules as the smallest particles of pure chemical substances that still retain their composition and chemical properties; this definition breaks down since many substances in ordinary experience, such as rocks and metals, are composed of large crystalline networks of chemically bonded atoms or ions, but are not made of discrete molecules.
Molecules are held together by ionic bonding. Several types of non-metal elements exist only as molecules in the environment. For example, hydrogen only exists as hydrogen molecule. A molecule of a compound is made out of two or more elements. A covalent bond is a chemical bond; these electron pairs are termed shared pairs or bonding pairs, the stable balance of attractive and repulsive forces between atoms, when they share electrons, is termed covalent bonding. Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, is the primary interaction occurring in ionic compounds; the ions are atoms that have lost one or more electrons and atoms that have gained one or more electrons. This transfer of electrons is termed electrovalence in contrast to covalence. In the simplest case, the cation is a metal atom and the anion is a nonmetal atom, but these ions can be of a more complicated nature, e.g. molecular ions like NH4+ or SO42−. An ionic bond is the transfer of electrons from a metal to a non-metal for both atoms to obtain a full valence shell.
Most molecules are far too small to be seen with the naked eye. DNA, a macromolecule, can reach macroscopic sizes, as can molecules of many polymers. Molecules used as building blocks for organic synthesis have a dimension of a few angstroms to several dozen Å, or around one billionth of a meter. Single molecules cannot be observed by light, but small molecules and the outlines of individual atoms may be traced in some circumstances by use of an atomic force microscope; some of the largest molecules are supermolecules. The smallest molecule is the diatomic hydrogen, with a bond length of 0.74 Å. Effective molecular radius is the size; the table of permselectivity for different substances contains examples. The chemical formula for a molecule uses one line of chemical element symbols and sometimes al
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding with the metal involves formal donation of one or more of the ligand's electron pairs; the nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, redox. Ligand selection is a critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, environmental chemistry. Ligands are classified in many ways, including: charge, the identity of the coordinating atom, the number of electrons donated to the metal.
The size of a ligand is indicated by its cone angle. The composition of coordination complexes have been known since the early 1800s, such as Prussian blue and copper vitriol; the key breakthrough occurred when Alfred Werner reconciled isomers. He showed, among other things, that the formulas of many cobalt and chromium compounds can be understood if the metal has six ligands in an octahedral geometry; the first to use the term "ligand" were Alfred Stock and Carl Somiesky, in relation to silicon chemistry. The theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the inexplicable isomers, he resolved the first coordination complex called hexol into optical isomers, overthrowing the theory that chirality was associated with carbon compounds. In general, ligands are viewed as the metals as electron acceptors; this is because the ligand and central metal are bonded to one another, the ligand is providing both electrons to the bond instead of the metal and ligand each providing one electron.
Bonding is described using the formalisms of molecular orbital theory. The HOMO can be of ligands or metal character. Ligands and metal ions can be ordered in many ways. Metal ions preferentially bind certain ligands. In general,'hard' metal ions prefer weak field ligands, whereas'soft' metal ions prefer strong field ligands. According to the molecular orbital theory, the HOMO of the ligand should have an energy that overlaps with the LUMO of the metal preferential. Metal ions bound to strong-field ligands follow the Aufbau principle, whereas complexes bound to weak-field ligands follow Hund's rule. Binding of the metal with the ligands results in a set of molecular orbitals, where the metal can be identified with a new HOMO and LUMO and a certain ordering of the 5 d-orbitals. In an octahedral environment, the 5 otherwise degenerate d-orbitals split in sets of 2 and 3 orbitals. 3 orbitals of low energy: dxy and dyz 2 of high energy: dz2 and dx2−y2The energy difference between these 2 sets of d-orbitals is called the splitting parameter, Δo.
The magnitude of Δo is determined by the field-strength of the ligand: strong field ligands, by definition, increase Δo more than weak field ligands. Ligands can now be sorted according to the magnitude of Δo; this ordering of ligands is invariable for all metal ions and is called spectrochemical series. For complexes with a tetrahedral surrounding, the d-orbitals again split into two sets, but this time in reverse order. 2 orbitals of low energy: dz2 and dx2−y2 3 orbitals of high energy: dxy and dyzThe energy difference between these 2 sets of d-orbitals is now called Δt. The magnitude of Δt is smaller than for Δo, because in a tetrahedral complex only 4 ligands influence the d-orbitals, whereas in an octahedral complex the d-orbitals are influenced by 6 ligands; when the coordination number is neither octahedral nor tetrahedral, the splitting becomes correspondingly more complex. For the purposes of ranking ligands, the properties of the octahedral complexes and the resulting Δo has been of primary interest.
The arrangement of the d-orbitals on the central atom, has a strong effect on all the properties of the resulting complexes. E.g. the energy differences in the d-orbitals has a strong effect in the optical absorption spectra of metal complexes. It turns out that valence electrons occupying orbitals with significant 3 d-orbital character absorb in the 400–800 nm region of the spectrum; the absorption of light by these electrons can be correlated to the ground state of the metal complex, which reflects the bonding properties of the ligands. The relative change in energy of the d-orbitals as a function of the field-strength of the ligands is described in Tanabe–Sugano diagrams. In cases where the ligand has low energy LUMO, such orbitals participate in the bonding; the metal–ligand bond can be further stabilised by a formal donation of electron density back to the ligand in a process known as back-bonding. In this case a filled, c
The Scientist (magazine)
The Scientist is a professional magazine intended for life scientists. Coverage includes reviews of noticed research papers, informing its audience of current research, updates to technology, updates to career information, profiles of scientists achieving notoriety, as well as other columns and reports of interest to its audience; the editor-in-chief is Robert Grant. The magazine is available in print and online; the Scientist was published by the Faculty of 1000 until October 2011. Its closure was announced in October 2011, but the LabX Media Group announced its intent to purchase and continue publishing it; the Group acquired the magazine at the end of October 2011. The Scientist was founded by Eugene Garfield, its aim is to provide print and online coverage of the latest developments in life sciences research and business. Subject matter covered by the magazine includes: Science policy Careers Financial topics Groundbreaking research Industry innovations Economics of science Scientific ethics Profiles of scientists Lab tools Hot papers Product spotlight, guidesStarting with the May 2010 issue, additional sections and features were added from the Faculty of 1000.
The additional content includes reviews of rated research papers and profiles of up-and-coming scientists. Since 2003, The Scientist has conducted "best places to work" surveys: one for postdoctoral researchers in all sectors, one for all life scientists working in industry, one for all life scientists working in academia; these surveys aim to find what aspects of the workplace are most important for job satisfaction and which institutions measure up to those standards. Throughout the year, The Scientist publishes overviews of these surveys' results, highlighting the top-ranking institutions; the Scientist conducts an annual survey of researchers and industry executives across various life science disciplines to learn about their income and job satisfaction. This is a valued resource amongst science professionals. Results are published annually. Since 2008, The Scientist has conferred awards for the top innovations in science technology: Nominations are submitted. In 2007, The Scientist started recognizing those laboratories which were best at using the Internet to further science.
Labs using YouTube, Wikipedia, JoVE, other online tools to best collaborate and research were nominated by readers around the world. Every year, the magazine invites scientists to contribute videos and offers awards in various categories; the Scientist offers a website that complements the print version by offering life science news and interactive multimedia features. The current month's magazine content, news blogs, podcasts are available with registration, while premium subscribers are given access to the magazine's archives of articles and editorials. In 2011, The Scientist launched a Facebook page to deliver its content in the social media realm; the page now has more than 1.5 million page likes and fosters a engaged community of readers. The following year, The Scientist launched special interest Facebook pages to share the latest research developments in six different life science topics; these pages boast a combined viewership of more than 2.6 million page views: Cancer Research Techniques Cell Biology Research Genetic Engineering Techniques Microbiology & Immunology Neuroscience Research Techniques Stem Cell & Regenerative Therapy The Scientist has won many awards, including most recently: 2011 Gold'Eddie' Award for Best Business-to-Business Science Magazine, Full Issue 2011 Silver'Eddie' Award for Best Business-to-Business Science Magazine, Full Issue 2011 Gold'Eddie' Award for Best Business-to-Business Single Science Article 2011 Bronze'Eddie' Award for Best Business-to-Business Single Science Article 2011 Silver'Eddie' Award for Best Business-to-Business News Coverage 2010 Gold'Eddie' Award for Best Business-to-Business Science Website 2010 Gold'Eddie' Award for Best Business-to-Business Science Magazine 2010 Gold'Eddie' Award for Best Business-to-Business Single Science Article 2009 Gold'Eddie' Award for Best Business-to-Business Science Website 2009 Gold'Eddie' Award for Best Business-to-Business Science Magazine 2009 Gold'Eddie' Award for Best Business-to-Business Single Science Article 2009 Magazine of the year, circulation less than 80,000 2008 Magazine of the year, circulation less than 80,000 2007 Nomination as one of the Top 10 Business-to-Business Magazines 2007 Gold for Best Publication Redesign 2007 Silver for Best Individual/Company Profile for Ishani Ganguli’s "A Complementary Pathway" 2008 Gold'Eddie' Award for Best Business-to-Business Science Magazine 2008 Gold'Eddie' Award for Best Business-to-Business Single Science Article 2007 Gold'Eddie' Award for Best Business-to-Business Science Magazine 2006 Gold'Eddie' Award for Best Business-to-Business Science Magazine Official website
Protein Data Bank
The Protein Data Bank is a database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The data obtained by X-ray crystallography, NMR spectroscopy, or cryo-electron microscopy, submitted by biologists and biochemists from around the world, are accessible on the Internet via the websites of its member organisations; the PDB is overseen by an organization called the Worldwide Protein Data Bank, wwPDB. The PDB is a key in areas such as structural genomics. Most major scientific journals, some funding agencies, now require scientists to submit their structure data to the PDB. Many other databases use protein structures deposited in the PDB. For example, SCOP and CATH classify protein structures, while PDBsum provides a graphic overview of PDB entries using information from other sources, such as Gene ontology. Two forces converged to initiate the PDB: 1) a small but growing collection of sets of protein structure data determined by X-ray diffraction.
In 1969, with the sponsorship of Walter Hamilton at the Brookhaven National Laboratory, Edgar Meyer began to write software to store atomic coordinate files in a common format to make them available for geometric and graphical evaluation. By 1971, one of Meyer's programs, SEARCH, enabled researchers to remotely access information from the database to study protein structures offline. SEARCH was instrumental in enabling networking, thus marking the functional beginning of the PDB; the Protein Data Bank was announced in October 1971 in Nature New Biology as a joint venture between Cambridge Crystallographic Data Centre, UK and Brookhaven National Laboratory, USA. Upon Hamilton's death in 1973, Tom Koeztle took over direction of the PDB for the subsequent 20 years. In January 1994, Joel Sussman of Israel's Weizmann Institute of Science was appointed head of the PDB. In October 1998, the PDB was transferred to the Research Collaboratory for Structural Bioinformatics; the new director was Helen M. Berman of Rutgers University.
In 2003, with the formation of the wwPDB, the PDB became an international organization. The founding members are PDBe, RCSB, PDBj; the BMRB joined in 2006. Each of the four members of wwPDB can act as deposition, data processing and distribution centers for PDB data; the data processing refers to the fact that annotate each submitted entry. The data are automatically checked for plausibility; the PDB database is updated weekly. The PDB holdings list is updated weekly; as of 17 October 2018, the breakdown of current holdings is as follows: 120,052 structures in the PDB have a structure factor file. 9,734 structures have an NMR restraint file. 3,486 structures in the PDB have a chemical shifts file. 2,531 structures in the PDB have a 3DEM map file deposited in EM Data BankThese data show that most structures are determined by X-ray diffraction, but about 10% of structures are now determined by protein NMR. When using X-ray diffraction, approximations of the coordinates of the atoms of the protein are obtained, whereas estimations of the distances between pairs of atoms of the protein are found through NMR experiments.
Therefore, the final conformation of the protein is obtained, in the latter case, by solving a distance geometry problem. A few proteins are determined by cryo-electron microscopy; the significance of the structure factor files, mentioned above, is that, for PDB structures determined by X-ray diffraction that have a structure file, the electron density map may be viewed. The data of such structures is stored on the "electron density server". In the past, the number of structures in the PDB has grown at an exponential rate, passing the 100 registered structures milestone in 1982, the 1,000 in 1993, the 10,000 in 1999, the 100,000 in 2014. However, since 2007, the rate of accumulation of new protein structures appears to have plateaued; the file format used by the PDB was called the PDB file format. This original format was restricted by the width of computer punch cards to 80 characters per line. Around 1996, the "macromolecular Crystallographic Information file" format, mmCIF, an extension of the CIF format started to be phased in.
MmCIF is now the master format for the PDB archive. An XML version of this format, called PDBML, was described in 2005; the structure files can be downloaded in any of these three formats. In fact, individual files are downloaded into graphics packages using web addresses: For PDB format files, use, e.g. http://www.pdb.org/pdb/files/4hhb.pdb.gz or http://pdbe.org/download/4hhb For PDBML files, use, e.g. http://www.pdb.org/pdb/files/4hhb.xml.gz or http://pdbe.org/pdbml/4hhbThe "4hhb" is the PDB identifier. Each structure published in PDB receives a four-character alphanumeric identifier, its PDB ID; the structure files may be viewed using one of several free and open source computer programs, including Jmol, Pymol, VMD, Rasmol. Other non-free, shareware programs
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – polypeptides – formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may be called a residue indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is identified as a peptide, rather than a protein. To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, hydrophobic packing. To understand the functions of proteins at a molecular level, it is necessary to determine their three-dimensional structure; this is the topic of the scientific field of structural biology, which employs techniques such as X-ray crystallography, NMR spectroscopy, dual polarisation interferometry to determine the structure of proteins.
Protein structures range in size from tens to several thousand amino acids. By physical size, proteins are classified as nanoparticles, between 1–100 nm. Large aggregates can be formed from protein subunits. For example, many thousands of actin molecules assemble into a microfilament. A protein undergoes reversible structural changes in performing its biological function; the alternative structures of the same protein are referred to as different conformational isomers, or conformations, transitions between them are called conformational changes. There are four distinct levels of protein structure; the primary structure of a protein refers to the sequence of amino acids in the polypeptide chain. The primary structure is held together by peptide bonds that are made during the process of protein biosynthesis; the two ends of the polypeptide chain are referred to as the carboxyl terminus and the amino terminus based on the nature of the free group on each extremity. Counting of residues always starts at the N-terminal end, the end where the amino group is not involved in a peptide bond.
The primary structure of a protein is determined by the gene corresponding to the protein. A specific sequence of nucleotides in DNA is transcribed into mRNA, read by the ribosome in a process called translation; the sequence of amino acids in insulin was discovered by Frederick Sanger, establishing that proteins have defining amino acid sequences. The sequence of a protein is unique to that protein, defines the structure and function of the protein; the sequence of a protein can be determined by methods such as Edman degradation or tandem mass spectrometry. However, it is read directly from the sequence of the gene using the genetic code, it is recommended to use the words "amino acid residues" when discussing proteins because when a peptide bond is formed, a water molecule is lost, therefore proteins are made up of amino acid residues. Post-translational modification such as phosphorylations and glycosylations are also considered a part of the primary structure, cannot be read from the gene.
For example, insulin is composed of 51 amino acids in 2 chains. One chain has 31 amino acids, the other has 20 amino acids. Secondary structure refers to regular local sub-structures on the actual polypeptide backbone chain. Two main types of secondary structure, the α-helix and the β-strand or β-sheets, were suggested in 1951 by Linus Pauling et al; these secondary structures are defined by patterns of hydrogen bonds between the main-chain peptide groups. They have a regular geometry, being constrained to specific values of the dihedral angles ψ and φ on the Ramachandran plot. Both the α-helix and the β-sheet represent a way of saturating all the hydrogen bond donors and acceptors in the peptide backbone; some parts of the protein do not form any regular structures. They should not be confused with random coil, an unfolded polypeptide chain lacking any fixed three-dimensional structure. Several sequential secondary structures may form a "supersecondary unit". Tertiary structure refers to the three-dimensional structure of monomeric and multimeric protein molecules.
The α-helixes and β-pleated-sheets are folded into a compact globular structure. The folding is driven by the non-specific hydrophobic interactions, the burial of hydrophobic residues from water, but the structure is stable only when the parts of a protein domain are locked into place by specific tertiary interactions, such as salt bridges, hydrogen bonds, the tight packing of side chains and disulfide bonds; the disulfide bonds are rare in cytosolic proteins, since the cytosol is a reducing environment. Quaternary structure is the three-dimensional structure consisting of the aggregation of two or more individual polypeptide chains that operate as a single functional unit; the resulting multimer is stabilized by the same non-covalent interactions and disulfide bonds as in tertiary structure. There are many possible quaternary structure organisations. Complexes of two or more polypeptides are called multimers, it would be called a dimer if it contains two subunits, a trimer if it contains three subunits, a tetramer if it contains four subunits, a pentamer if it contains five subunits.
The subunits are related to one another by symmetry operations, such as a 2-fold axis in a dimer. Multimers made up of identical subunits are referred to with a prefix of "homo-" and those made up of different subuni
Photosystem II is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants and cyanobacteria. Within the photosystem, enzymes capture photons of light to energize electrons that are transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol; the energized electrons are replaced by oxidizing water to form molecular oxygen. By replenishing lost electrons with electrons from the splitting of water, photosystem II provides the electrons for all of photosynthesis to occur; the hydrogen ions generated by the oxidation of water help to create a proton gradient, used by ATP synthase to generate ATP. The energized electrons transferred to plastoquinone are used to reduce NADP+ to NADPH or are used in non-cyclic electron flow; the core of PSII consists of a pseudo-symmetric heterodimer of two homologous proteins D1 and D2. Unlike the reaction centers of all other photosystems in which the positive charge sitting on the chlorophyll dimer that undergoes the initial photoinduced charge separation is shared by the two monomers, in intact PSII the charge is localized on one chlorophyll molecule.
Because of this, P680+ is oxidizing and can take part in the splitting of water. Photosystem II is composed of around 20 subunits as well as other accessory, light-harvesting proteins; each photosystem II contains at least 99 cofactors: 35 chlorophyll a, 12 beta-carotene, two pheophytin, two plastoquinone, two heme, one bicarbonate, 20 lipid molecules, the Mn4CaO5 cluster, one non heme Fe2+ and two putative Ca2+ ions per monomer. There are several crystal structures of photosystem II; the PDB accession codes for this protein are 3WU2, 3BZ1, 3BZ2, 2AXT, 1S5L, 1W5C, 1ILX, 1FE1, 1IZL. The oxygen-evolving complex is the site of water oxidation, it is a metallo-oxo cluster comprising one divalent calcium ion. When it oxidizes water, producing oxygen gas and protons, it sequentially delivers the four electrons from water to a tyrosine sidechain and to P680 itself; the first structural model of the oxygen-evolving complex was solved using X-ray crystallography from frozen protein crystals with a resolution of 3.8Å in 2001.
Over the next years the resolution of the model was increased to 2.9Å. While obtaining these structures was in itself a great feat, they did not show the oxygen-evolving complex in full detail. In 2011 the OEC of PSII was resolved to a level of 1.9Å revealing five oxygen atoms serving as oxo bridges linking the five metal atoms and four water molecules bound to the Mn4CaO5 cluster. At this stage, it is suggested that the structures obtained by X-ray crystallography are biased, since there is evidence that the manganese atoms are reduced by the high-intensity X-rays used, altering the observed OEC structure; this incentivized researchers to take their crystals to a different X-ray facilities, called X-ray Free Electron Lasers, such as SLAC in the USA. In 2014 the structure observed in 2011 was confirmed. Knowing the structure of Photosystem II did not suffice to reveal how it works exactly. So now the race has started to solve the structure of Photosystem II at different stages in the mechanistic cycle.
Structures of the S1 state and the S3 state's have been published simultaneously from two different groups, showing the addition of an oxygen molecule designated O6 between Mn1 and Mn4, suggesting that this may be the site on the oxygen evolving complex, where oxygen is produced. Photosynthetic water splitting is one of the most important reactions on the planet, since it is the source of nearly all the atmosphere's oxygen. Moreover, artificial photosynthetic water-splitting may contribute to the effective use of sunlight as an alternative energy-source; the mechanism of water oxidation is still not elucidated, but we know many details about this process. The oxidation of water to molecular oxygen requires extraction of four electrons and four protons from two molecules of water; the experimental evidence that oxygen is released through cyclic reaction of oxygen evolving complex within one PSII was provided by Pierre Joliot et al. They have shown that, if dark-adapted photosynthetic material is exposed to a series of single turnover flashes, oxygen evolution is detected with typical period-four damped oscillation with maxima on the third and the seventh flash and with minima on the first and the fifth flash.
Based on this experiment, Bessel Kok and co-workers introduced a cycle of five flash-induced transitions of the so-called S-states, describing the four redox states of OEC: When four oxidizing equivalents have been stored, OEC returns to its basic S0-state. In the absence of light, the OEC will "relax" to the S1 state; the S1 state is considered to consist of manganese ions with oxidation states of Mn3+, Mn3+, Mn4+, Mn4+. The intermediate S-states were proposed by Jablonsky and Lazar as a regulatory mechanism and link between S-states and tyrosine Z. In 2012, Renger expressed the idea of internal changes of water molecules into typical oxides in different S-states during water splitting. In 201
Weizmann Institute of Science
The Weizmann Institute of Science is a public research university in Rehovot, established in 1934, 14 years before the State of Israel. It differs from other Israeli universities in that it offers only graduate and postgraduate degrees in the natural and exact sciences, it is a multidisciplinary research center, with around 3,800 scientists, postdoctoral fellows, Ph. D. and M. Sc. students, scientific and administrative staff working at the Institute. As of 2019, 6 Nobel laureates and 3 Turing Award winners have been associated with the Weizmann Institute of Science. Founded in 1934 by Chaim Weizmann and his first team, among them Benjamin M. Bloch, as the Daniel Sieff Research Institute. Weizmann had offered the post of director to Nobel Prize laureate Fritz Haber, but took over the directorship himself after Haber's death en route to Palestine. Before he became President of the State of Israel in February 1949, Weizmann pursued his research in organic chemistry at its laboratories; the institute was renamed the Weizmann Institute of Science in his honor on November 2, 1949, in agreement with the Sieff family.
WEIZAC, one of the world’s first electronic computers was locally built by the institute in 1954–1955 and was recognized by the IEEE in 2006 as a milestone achievement in the history of electrical and electronic engineering. In 1959, the institute set up a wholly owned subsidiary called Yeda Research and Development Company to commercialize inventions made at the institute. By 2013 the institute was earning between $50 and $100 million in royalties annually on marketed drugs including Copaxone and Erbitux; the Weizmann Institute presently has about 2,500 students, postdoctoral fellows and faculty, awards M. Sc. and Ph. D. degrees in mathematics, computer science, chemistry and biology, as well as several interdisciplinary programs. The symbol of the Weizmann Institute of Science is the multibranched Ficus tree. Undergraduates and recent graduates must apply to M. Sc. programs, while those earning an M. Sc. or an MD can apply directly to Ph. D. programs. Full fellowships are given to all students.
In addition to its academic programs, the Weizmann Institute runs programs for youth, including science clubs and competitions. The Bessie F. Lawrence International Summer Science Institute accepts high-school graduates from all over the world for a four-week, science-based summer camp; the Clore Garden of Science, which opened in 1999, is the world’s first interactive outdoor science museum. In 2017, the Weizmann Institute made the Academic Ranking of World Universities at an unspecified place between 101 and 150 and the U. S. News' Best Global Universities list in 104th place. In the 2017 CWTS Leiden Ranking, based on the proportion of a university's scientific papers published between 2012 and 2015 that made the 10% most cited in their field, it was ranked 13th in the world and first in Israel. Chaim Weizmann Meyer Weisgal Abba Eban Meyer Weisgal Albert Sabin Israel Dostrovsky Michael Sela Aryeh Dvoretzky Haim Harari Ilan Chet Daniel Zajfman The nonscientists Abba Eban and Meyer Weisgal were assisted by scientific directors, as was Weizmann himself owing to his duties as the first president of Israel.
The following persons held the position of scientific director: Ernst David Bergmann Amos de-Shalit Shneior Lifson Gerhard M. J. Schmidt List of universities in Israel Science and technology in Israel Weizmann Institute of Science Website