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Proteins chains

Protein tertiary structure is also influenced by the environment In water a globu lar protein usually adopts a shape that places its hydrophobic groups toward the interior with Its polar groups on the surface where they are solvated by water molecules About 65% of the mass of most cells is water and the proteins present m cells are said to be m their native state—the tertiary structure m which they express their biological activ ity When the tertiary structure of a protein is disrupted by adding substances that cause the protein chain to unfold the protein becomes denatured and loses most if not all of Its activity Evidence that supports the view that the tertiary structure is dictated by the primary structure includes experiments m which proteins are denatured and allowed to stand whereupon they are observed to spontaneously readopt their native state confer matron with full recovery of biological activity... [Pg.1146]

Knowing how the protein chain is folded is a key ingredient m understanding the mechanism by which an enzyme catalyzes a reaction Take carboxypeptidase A for exam pie This enzyme catalyzes the hydrolysis of the peptide bond at the C terminus It is... [Pg.1146]

Section 28 12 The start codon for protein biosynthesis is AUG which is the same as the codon for methionine Thus all proteins initially have methionine as their N terminal ammo acid but lose it subsequent to their formation The reaction responsible for extending the protein chain is nucleophilic acyl substitution... [Pg.1189]

Critical micelle concentration (Section 19 5) Concentration above which substances such as salts of fatty acids aggre gate to form micelles in aqueous solution Crown ether (Section 16 4) A cyclic polyether that via lon-dipole attractive forces forms stable complexes with metal 10ns Such complexes along with their accompany mg anion are soluble in nonpolar solvents C terminus (Section 27 7) The amino acid at the end of a pep tide or protein chain that has its carboxyl group intact—that IS in which the carboxyl group is not part of a peptide bond Cumulated diene (Section 10 5) Diene of the type C=C=C in which a single carbon atom participates in double bonds with two others... [Pg.1280]

N terminus (Section 27 7) The amino acid at the end of a pep tide or protein chain that has its a ammo group intact that IS the a ammo group is not part of a peptide bond... [Pg.1289]

Quaternary structure (Section 27 22) Description of the way in which two or more protein chains not connected by chemical bonds are organized in a larger protein Quinone (Section 24 14) The product of oxidation of an ortho or para dihydroxybenzene denvative Examples of quinones include... [Pg.1292]

These appHcations are mosdy examples of homogeneous catalysis. Coordination catalysts that are attached to polymers via phosphine, siloxy, or other side chains have also shown promise. The catalytic specificity is often modified by such immobilization. Metal enzymes are, from this point of view, anchored coordination catalysts immobilized by the protein chains. Even multistep syntheses are possible using alternating catalysts along polymer chains. Other polynuclear coordination species, such as the homopoly and heteropoly ions, also have appHcations in reaction catalysis. [Pg.172]

Proteins are macromolecules that play many roles such as serving as enzymes or components of cell membranes and muscle. The antibodies that protect against invasion by foreign substances are themselves proteins. There are twenty-odd amino acids found regularly in most naturally occurring proteins. Because of the great length of protein chains and the various sequences of amino acids, the theoretic number of possible proteins is astronomical. The amino acid sequence is referred to as the primaiy structure of a protein. The pol eptide... [Pg.2132]

CB Anfinsen. Principles that govern the folding of protein chains. Science 181 223-238, 1973. [Pg.308]

Proteins are usually separated into two distinct functional classes passive structural materials, which are built up from long fibers, and active components of cellular machinery in which the protein chains are arranged in small compact domains, as we have discussed in earlier chapters. In spite of their differences in structure and function, both these classes of proteins contain a helices and/or p sheets separated by regions of irregular structure. In most cases the fibrous proteins contain specific repetitive amino acid sequences that are necessary for their specific three-dimensional structure. [Pg.283]

An elegant NMR experiment by the group of Lynn Jelinski at Cornell University has established that at least part of the microcrystals is built up from the polyalanine repeats in the protein chains. These experiments, which were made on C-enriched proteins produced by feeding the spiders C-labeled alanine, showed that there were two populations of alanine side chains, one ordered and oriented perpendicular to the fiber axis and a second less ordered. Jelinski s interpretation is that parts of the polyalanine sequences are incorporated as p strands in the microcrystals with an orientation parallel to the fiber axis. Whether or not the Gly-Gly-X repeats also form P strands in the microcrystals remains an open question. [Pg.290]

Very few self-sufficient viruses have only 60 protein chains in their shells. The satellite viruses do not themselves encode all of the functions required for their replication and are therefore not self-sufficient. The first satellite virus to be discovered, satellite tobacco necrosis virus, which is also one of the smallest known with a diameter of 180 A, has a protein shell of 60 subunits. This virus cannot replicate on its own inside a tobacco cell but needs a helper virus, tobacco necrosis virus, to supply the functions it does not encode. The RNA genome of the satellite virus has only 1120 nucleotides, which code for the viral coat protein of 195 amino acids but no other protein. With this minimal genome the satellite viruses are obligate parasites of the viruses that parasitize cells. [Pg.329]

Tomato bushy stunt virus is a T = 3 plant virus with 180 chemically identical subunits. Each polypeptide chain is divided into several domains. The subunits preserve quasi-equivalent packing in most contact regions by conformational differences of the protein chains, especially a large change in... [Pg.343]

Figure 18.11 Electron-density maps at different resolution show more detail at higher resolution, (a) At low resolution (5.0 A) individual groups of atoms are not resolved, and only the rodlike feature of an Figure 18.11 Electron-density maps at different resolution show more detail at higher resolution, (a) At low resolution (5.0 A) individual groups of atoms are not resolved, and only the rodlike feature of an <x helix can be deduced, (b) At medium resolution (3.0 A) the path of the polypeptide chain can be traced, and (c) at high resolution (1.5 A) individual atoms start to become resolved. Relevant parts of the protein chain (red) are superimposed on the electron densities (gray) The diagrams show one <x helix from a small protein, myohemerythrin. [Adapted from W.A. Hendrickson in Protein Engineering (eds. D.L. Oxender and C.F. Fox.), p. 11.
Acute Liver Damage Several compounds (e.g., dimethyl iiitrosoamine, carbon tetrachloride, and thioacetamide) cause necrosis of hepatocytes by inhibiting pro tein syndiesis at the translational level, i.e., by inhibiting the addition of new amino adds into the protein chain being sjTithetized. This is not, however, the only mechanism. Ethioiiine is a compound which inhibits protein synthesis bur doe not induce... [Pg.298]

Tertiary structure (Section 27.20) A description of how a protein chain is folded. [Pg.1295]

The structure of any molecule is a unique and specific aspect of its identity. Molecular structure reaches its pinnacle in the intricate complexity of biological macromolecules, particularly the proteins. Although proteins are linear sequences of covalently linked amino acids, the course of the protein chain can turn, fold, and coil in the three dimensions of space to establish a specific, highly ordered architecture that is an identifying characteristic of the given protein molecule (Figure 1.11). [Pg.14]

FIGURE 22.18 Model of the R. viridis reaction center, (a, b) Two views of the ribbon diagram of the reaction center. Mand L subunits appear in purple and blue, respectively. Cytochrome subunit is brown H subunit is green. These proteins provide a scaffold upon which the prosthetic groups of the reaction center are situated for effective photosynthedc electron transfer. Panel (c) shows the spatial relationship between the various prosthetic groups (4 hemes, P870, 2 BChl, 2 BPheo, 2 quinones, and the Fe atom) in the same view as in (b), but with protein chains deleted. [Pg.725]

The simplest NHIP is rubredoxin, in which the single iron atom is coordinated (Fig. 25.9a) to 4 S atoms belonging to cysteine residues in the protein chain. It differs from the other Fe-S proteins in having no labile sulfur (i.e. inorganic sulfur which can be liberated as H2S by treatment with mineral acid sulfur atoms of this type are not part of the protein, but form bridges between Fe atoms.)... [Pg.1102]

Molecular construction for a protein chain is just about impossible using the Z-matrix (unless you are particularly good at crossword puzzles). As 1 mentioned in Chapter 10, there are also immense practical difficulties associated with symmetric, cyclic and linear structures, and as time went by people began to question the use of the Z-matrix. [Pg.244]

Biochemists have different problems in mind they want to divide parts of a protein chain into regions of interest that ought to be treated quantum-mechanically and the remainder of the chain that can be treated according to the methods of molecular mechanics. [Pg.263]

Consider, for example, the protein shown in Figure 15.7. The bottom left-hand amino acid is valine, which is linked to proline. Suppose for the sake of argument that we wanted to treat this valine quantum-mechanically and the rest of the protein chain according to the methods of molecular mechanics. We would have to draw a QM/MM boundary somewhere between valine and the rest of the protein. The link atoms define the boundary between the QM and the MM regions. A great deal of care has to go into this choice of boundary. The boundary should not give two species whose chemical properties are quite different from those implied by the structural formulae on either side of this boundary. [Pg.263]

Nucleophilic aromatic substitution is much less common than electrophilic substitution but nevertheless does have certain uses. One such use is the reaction of proteins with 2,4-dinitrofluorobenzene, known as Sanger s reagent, to attach a "label" to the terminal NH2 group of the amino acid at one end of the protein chain. [Pg.572]

This thiol-disulfide interconversion is a key part of numerous biological processes. WeTJ see in Chapter 26, for instance, that disulfide formation is involved in defining the structure and three-dimensional conformations of proteins, where disulfide "bridges" often form cross-links between q steine amino acid units in the protein chains. Disulfide formation is also involved in the process by which cells protect themselves from oxidative degradation. A cellular component called glutathione removes potentially harmful oxidants and is itself oxidized to glutathione disulfide in the process. Reduction back to the thiol requires the coenzyme flavin adenine dinucleotide (reduced), abbreviated FADH2. [Pg.668]

Figure 26.9 X-ray crystal structure of citrate synthase. Part (a) is a space-filling model and part (b) is a ribbon model, which emphasizes the a-helical segments of the protein chain and indicates that the enzyme is dimeric that is, it consists of two identical chains held together by hydrogen bonds and other intermolecular attractions. Part (cl is a close-up of the active site in which oxaloacetate and an unreactive acetyl CoA mimic are bound. Figure 26.9 X-ray crystal structure of citrate synthase. Part (a) is a space-filling model and part (b) is a ribbon model, which emphasizes the a-helical segments of the protein chain and indicates that the enzyme is dimeric that is, it consists of two identical chains held together by hydrogen bonds and other intermolecular attractions. Part (cl is a close-up of the active site in which oxaloacetate and an unreactive acetyl CoA mimic are bound.
Proteins have four levels of structure. Primary structure describes a protein s amino acid sequence secondary structure describes how segments of the protein chain orient into regular patterns—either a-helix or /3-pleated sheet tertiary structure describes how the entire protein molecule coils into an overall three-dimensional shape and quaternary structure describes how individual protein molecules aggregate into larger structures. [Pg.1050]

C-terminal amino acid (Section 26.4) The amino acid with a free -C02H group at the end of a protein chain. [Pg.1237]


See other pages where Proteins chains is mentioned: [Pg.1148]    [Pg.331]    [Pg.86]    [Pg.77]    [Pg.267]    [Pg.14]    [Pg.146]    [Pg.191]    [Pg.329]    [Pg.332]    [Pg.336]    [Pg.1148]    [Pg.119]    [Pg.172]    [Pg.1099]    [Pg.1101]    [Pg.1031]   


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Atlas of Protein Side-Chain Interactions

Bonds between protein chains

Calcium/calmodulin-dependent protein kinases myosin light chain kinase phosphorylation

Chain length factor proteins

Chains of proteins

Chains, robust electron transfer protein design

Electron transport chain iron-sulfur proteins

Electron transport chain protein machines

Fatty acids, binding protein branched chain

Globular proteins hydrophobic side chains, packing

Glycosaminoglycans chains in proteins

Heavy-chain binding protein

Hydrogen bond chains in proteins

Hydrogen bonding between protein side chains

Immunoglobulin heavy chain binding protein

Main Chain Anion Binding Sites in Proteins Nests

Methylation of protein side chains

Microtubule-associated protein 1 light chain

Myosin light chain interacting protein

Phosphoadenylation of protein side chains

Phosphorylation of protein side chains

Photosynthetic phosphorylation of protein side chains

Polymerase chain reaction proteins

Polypeptide chains, elongation protein synthesis

Polypeptide-chain-binding proteins

Polyubiquitin-chain-binding Proteins

Protein A naturally occurring polymeric chain of L-amino acids linked together

Protein Binding through Side Chains

Protein chain folding

Protein chain ligation

Protein chain photosystem

Protein chain shortening

Protein chain thickness

Protein chain, atomic resolution

Protein covalent links between chains

Protein folding, apolar side chains

Protein hydrogen bonding of side chains

Protein kinase myosin light chain

Protein long-chain

Protein main-chain conformation

Protein side chain groups, reactions

Protein side-chain modeling

Protein side-chain peptides

Protein side-chain reactivities

Protein side-chains

Protein side-chains 200 INDEX

Protein synthesis chain elongation

Protein synthesis chain initiation

Protein synthesis chain termination

Protein synthesis polypeptide chain

Protein! s) polypeptide chains

Protein-based machines electron transport chain

Protein-lipid respiratory chain complexes

Proteins - continued peptide chain elongation

Proteins - continued peptide chain termination

Proteins Are Polymer Chains Composed of Amino Acid Monomers

Proteins amino acid chain

Proteins amino acid side-chain

Proteins aromatic side-chains

Proteins enzymatic cleavage, polypeptide chains

Proteins lysine side-chains, modification

Proteins main-chain anion binding sites

Proteins side chain resonances

Proteins side chain vibrations

Proteins side-chain arrangement

Proteins side-chain reactions

Proteins, polypeptide chain

Proteins, polypeptide chain folding

Redox protein chain

Side chain conformation tertiary protein structure

Single chain Fv protein

Spectrophotometric assays for protein amino acid side chains

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