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Proteins Amino acid activation

The asterisk signifies an asymmetric carbon. AH of the amino acids, except glycine, have two optically active isomers designated D- or L-. Isoleucine and threonine also have centers of asymmetry at their P-carbon atoms (1,10). Protein amino acids are of the L-a-form (1,10) as illustrated in Table 1. [Pg.269]

S. U. Schenk, F. Lambein, and D. Werner, Broad antifungal activity of P-isoxyzoli-nonyl-alanine, a non-protein amino acid from roots of pea (Pisum. sativum L.). seedlings, Biol. Fertil. Soils. 11 207, (1991). [Pg.222]

As we have noted, the outcome of a virus infection is the synthesis of viral nucleic acid and viral protein coats. In effect, the virus takes over the biosynthetic machinery of the host and uses it for its own synthesis. A few enzymes needed for virus replication may be present in the virus particle and may be introduced into the cell during the infection process, but the host supplies everything else energy-generating system, ribosomes, amino-acid activating enzymes, transfer RNA (with a few exceptions), and all soluble factors. The virus genome codes for all new proteins. Such proteins would include the coat protein subunits (of which there are generally more than one kind) plus any new virus-specific enzymes. [Pg.123]

A further important group of derivatives is that of amino acids activated by phosphoric acid or its esters. In nature, phosphorylation processes play an important activating role in peptide and protein synthesis. [Pg.128]

The active site of an enzyme is generally a pocket or cleft that is specialized to recognize specific substrates and catalyze chemical transformations. It is formed in the three-dimensional structure by a collection of different amino acids (active-site residues) that may or may not be adjacent in the primary sequence. The interactions between the active site and the substrate occur via the same forces that stabilize protein structure hydrophobic interactions, electrostatic interactions (charge-charge), hydrogen bonding, and van der Waals interactions. Enzyme active sites do not simply bind substrates they also provide catalytic groups to facilitate the chemistry and provide specific interactions that stabilize the formation of the transition state for the chemical reaction. [Pg.94]

Arteel and Sies (1999) examined procyanidin oligomers of different size, isolated from the seeds of Theobroma cacao, for their ability to protect against nitration of tyrosine. Serraino and others (2003) investigated antioxidant activity of the blackberry juice and cyanidin-3-O-glucoside on endothelial dysfunction in cells and in vascular rings exposed to peroxynitrite. However, more work is needed in this area, and the confounding effects of oxidized protein/amino acids in the diet need to be elucidated. [Pg.278]

It is clear that in this brief overview of molecular biology, we have not covered a number of important areas that have an important impact on the study of metalloproteins. These include molecular cloning and recombinant DNA technology, which allow proteins to be over-expressed and individual amino acids to be mutated to any other of the 19 protein amino acids genome and proteome analysis that enables the sequences of all the genes of the entire organisms to be determined, and the quantification, localization, interactions and, where possible, activities and identification of all of the proteins in an organism,... [Pg.75]

Like amino acid activation (see p. 248), protein biosynthesis (translation) takes piace in the cytopiasm. it is cataiyzed by compiex nucieoprotein particies, the ribosomes, and mainiy requires GTP to cover its energy requirements. [Pg.250]

Energy requirements in protein synthesis are high. Four energy-rich phosphoric acid anhydride bonds are hydrolyzed for each amino acid residue. Amino acid activation uses up two energy-rich bonds per amino acid (ATP AMP + PP see p. 248), and two GTPs are consumed per elongation cycle. In addition, initiation and termination each require one GTP per chain. [Pg.252]

Ornithine is a metabolically quite active amino acid, and the important precursor of pyrrolidine nucleus, which is found in pyrrolizidine alkaloids. Ornithine itself is a non-protein amino acid formed mainly from L-glumate in plants, and synthesized from the urea cycle in animals as a result of the reaction catalyzed by enzymes in arginine. [Pg.73]

Why does mtDNA contain any protein genes, or why does mtDNA even exist It seems remarkable that the cells of our bodies make the 100 or so extra proteins (encoded in the nucleus) needed for replication, transcription, amino acid activation, and mitochondrial ribosome formation and bring these into the mitochondria for the sole purpose of permitting the synthesis there of 13 proteins. The explanation is not evident. What are the 13 proteins ... [Pg.1017]

The commercial availability of protected /V-methyl amino acids [(Me)Xaa] of many proteinogenic amino acids (as well as other V-alkyl amino acids), the availability of procedures for the synthesis of protected V-alkyl analogues of all the protein amino acids, and the availability of synthetic procedures for site-selective alkylation during SPPS (see Section 10.1.2.1) allows the alkylation of nearly all peptide bonds in a given parent peptide. The synthesis of a series of V-alkyl peptide analogues based on the sequence of a given bioactive peptide (linear or cyclic) in which each peptide bond is successively alkylated and evaluation of the biological activity of this series will be called herein A-alkyl-scan (for example Me-scan, Et-scan, etc.)... [Pg.217]

Siman R. and Noszek J. C. (1988). Excitatory amino acids activate calpain I and induce structural protein breakdown in vivo. Neuron 1 279-287. [Pg.102]


See other pages where Proteins Amino acid activation is mentioned: [Pg.121]    [Pg.92]    [Pg.83]    [Pg.414]    [Pg.251]    [Pg.128]    [Pg.1037]    [Pg.227]    [Pg.360]    [Pg.353]    [Pg.110]    [Pg.230]    [Pg.67]    [Pg.126]    [Pg.231]    [Pg.484]    [Pg.23]    [Pg.35]    [Pg.1564]    [Pg.280]    [Pg.286]    [Pg.1668]    [Pg.243]    [Pg.292]    [Pg.293]    [Pg.293]    [Pg.306]    [Pg.713]    [Pg.371]    [Pg.230]    [Pg.270]    [Pg.66]    [Pg.207]    [Pg.109]    [Pg.349]    [Pg.332]   
See also in sourсe #XX -- [ Pg.107 ]




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