Peptides tyrosine

Negative PLS coefficient in region accomodating peptide tyrosine > small side-chain at residue 30 favors binding... 

Peptide Tyrosine Tyrosine (PYY) PYY receptor 36-residue peptide amide Inhibit food digestion Solid-phase V"-Fmoc chemistry... 

Aponte, G. W., Park, K., Hess, R. Garcia, R., and Taylor, I. L. (1989). Meal-induced peptide tyrosine inhibition of pancreatic secretion in the rat. FASEB ]. 3,1949-1955. 

Bleich HE, Day AR, Ereer RJ, Glasel JA (1979) NMR rotating frame relaxation studies of intramolecular motion in peptides. Tyrosine ring motion in methionine-enkephalin. Biochem Biophys Res Commun 87 1146-1153... 

Peptide YY, also known as PYY or peptide tyrosine tyrosine, is the name of a human gene and protein. Peptide YY3 3g (PYY) is a linear polypeptide consisting of 36 amino adds with structural... 

MitcheU S, et al. Peptide tyrosine tyrosine levels are increased in patients with urea cycle disorders. Mol Genet Metab. 2012 106(l) 39-42. 

As constituents of proteins the amino-acids are important constituents of the food of animals. Certain amino-acids can be made in the body from ammonia and non-nitrogenous sources others can be made from other amino-acids, e.g. tyrosine from phenylalanine and cystine from methionine, but many are essential ingredients of the diet. The list of essential amino-acids depends partly on the species. See also peptides and proteins. 

Zhang and co-workers worked on the structure-based, computer-assisted search for low molecular weight, non-peptidic protein tyrosine phosphate IB (PTPIB) inhibitors, also using the DOCK methodology [89], They identified several potent and selective PTPIB inhibitors by saeening the ACD. 

The phenolic hydroxyl group of tyrosine, the imidazole moiety of histidine, and the amide groups of asparagine and glutamine are often not protected in peptide synthesis, since it is usually unnecessary. The protection of the hydroxyl group in serine and threonine (O-acetylation or O-benzylation) is not needed in the azide condensation procedure but may become important when other activation methods are used. 

Chymotrypsin (Section 27 10) A digestive enzyme that cat alyzes the hydrolysis of proteins Chymotrypsin selectively catalyzes the cleavage of the peptide bond between the car boxyl group of phenylalanine tyrosine or tryptophan and some other ammo acid... 

Pish protein concentrate and soy protein concentrate have been used to prepare a low phenylalanine, high tyrosine peptide for use with phenylketonuria patients (150). The process includes pepsin hydrolysis at pH 1.5 ptonase hydrolysis at pH 6.5 to Hberate aromatic amino acids gel filtration on Sephadex G-15 to remove aromatic amino acids incubation with papain and ethyl esters of L-tyrosine and L-tryptophan, ie, plastein synthesis and ultrafiltration (qv). The plastein has a bland taste and odor and does not contain free amino acids. Yields of 69.3 and 60.9% from PPG and soy protein concentrate, respectively, have been attained. 

Dynorphin may also influence nociception at the spinal level. The levels of prodynorphin mRNA and immunoreactive dynorphin increase in the chronic inflammatory arthritic model (158). Dynorphin also inhibits morphine or P-endorphin-induced analgesia in naive animals and enhances analgesia in tolerant animals, indicating that this peptide may have a regulatory role in opioid analgesia (159). This effect does not appear to be mediated by a classical opioid receptor, since des-tyrosine dynorphin, which does not bind to opioid receptors, also antagonizes morphine analgesia (160). 

The Dim ester was developed for the protection of the carboxyl function during peptide synthesis. It is prepared by transesterification of amino acid methyl esters with 2-(hydroxymethyl)-l,3-dithiane and Al(/-PrO)3 (reflux, 4 h, 75°, 12 torr, 75% yield). It is removed by oxidation [H2O2, (NH4)2Mo04 pH 8, H2O, 60 min, 83% yield]. Since it must be removed by oxidation it is not compatible with.sulfur-containing amino acids such as cysteine and methionine. Its suitability for other, easily oxidized amino acids (e.g., tyrosine and tryptophan) must also be questioned. It is stable to CF3CO2H and HCl/ether. - ... 

Figure 13.26 Schematic diagram of the SH2 domain from the Src tyrosine kinase with bound peptide. The SH2 domain (blue) comprises a central p sheet surrounded by two a helices. Three positively charged residues (green) are involved in binding the phosphotyrosine moiety of the bound peptide (red). (Adapted from G. Waksman et al.. Cell 72 779-790, 1993.)...

Certain amino acids and their derivatives, although not found in proteins, nonetheless are biochemically important. A few of the more notable examples are shown in Figure 4.5. y-Aminobutyric acid, or GABA, is produced by the decarboxylation of glutamic acid and is a potent neurotransmitter. Histamine, which is synthesized by decarboxylation of histidine, and serotonin, which is derived from tryptophan, similarly function as neurotransmitters and regulators. /3-Alanine is found in nature in the peptides carnosine and anserine and is a component of pantothenic acid (a vitamin), which is a part of coenzyme A. Epinephrine (also known as adrenaline), derived from tyrosine, is an important hormone. Penicillamine is a constituent of the penicillin antibiotics. Ornithine, betaine, homocysteine, and homoserine are important metabolic intermediates. Citrulline is the immediate precursor of arginine. 

Chymotrypsin shows a strong preference for hydrolyzing peptide bonds formed by the carboxyl groups of the aromatic amino acids, phenylalanine, tyrosine, and tryptophan. Flowever, over time chymotrypsin also hydrolyzes amide bonds involving amino acids other than Phe, Tyr, or Trp. Peptide bonds having leucine-donated carboxyls become particularly susceptible. Thus, the specificity... 

An isopropyl ether was developed as a phenol protective group that would be more stable to Lewis acids than would be an aryl benzyl ether. The isopropyl group has been tested for use in the protection of the phenolic oxygen of tyrosine during peptide synthesis."... 

Me2P(0)Cl, Et3N, CHCI3, 76% yield. The Dmp group was used to protect tyrosine for use in peptide synthesis. It is stable to IM HCl/MeOH, 1 MHCl/AcOH, CF3CO2H, HBr/AcOH, and H2/Pd-C. 

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