Peptide histidine methionine

PHI Peptide histidine isolcucine PHM Peptide histidine methionine Pi Inorganic phosphate PI Phosphatidylinositol PI-3,4-P2 Phosphatidylinositol 3, 4-biphosphate... 

Obal F Jr, Opp M, Cady AB, Johannsen L, Krueger JM. Prolactin, vasoactive intestinal peptide, and peptide histidine methionine elicit selective increases in REM sleep in rabbits. Brain Res 1989 490 292-300. 

PHM PEPTIDE HISTIDINE METHIONINE, phosphatase An enzyme that catalyses removal of a phosphate group. 

Octreotide blocks the release of serotonin and many other active peptides and has been effective in controlling diarrhea and flushing. It is reported to have direct inhibitory effects on intestinal secretion and stimulatory effects on intestinal absorption. Non-gastrin-secreting adenomas of the pancreas are tumors associated with profuse watery diarrhea. This condition has been referred to as Verner-Morrison syndrome, WDHA (watery diarrhea, hypokalemia, and achlorhydria) syndrome, pancreatic cholera, watery diarrhea syndrome, and VIPoma. Excessive secretion of VIP from a retroperitoneal or pancreatic tumor produces most of the clinical features. Excessive VIP is isolated in about half of patients, along with numerous other peptide hormones (peptide histidine methionine [PHM], serotonin,... 

PEG-ELS polyethylene glycol-electrolyte lavage solution PHM peptide histidine methionine VIP vasoactive intestinal peptide... 

VIP-producing tumors have been associated with the syndrome of WDHA. In a series of 28 cases of WDHA studied by Solcia and colleagues, VIP was present in 87% and peptide histidine methionine was present in 57% of cases.Growth hormone-releasing hormone and PP were present in 50% and 53% of cases, respectively. In addition to pancreatic endocrine tumors, ganglioneuromas and ganglioneuroblastomas have been associated with the syndrome of WDHA. 

Mentlein R, Gallwitz B, Schmidt WE. Dipeptidyl-peptidase IV hydrolyses gastric inhihitory polypeptide, glucagon-like peptide-1 (7-36) amide, peptide histidine methionine and is responsible for then-degradation in human serum. Eur 1 Biochem 1993 214 829-835. 

Early studies have shown that tryptophan, tyrosine, histidine, methionine and cysteine, either as free amino acids or as components of peptides, are excellent substrates for O2 oxidation reactions. Usually, reaction of O2 with amino acids is mostly described in terms of chemical quenching with the exception of tryptophan, for which collisional deactivation as the result of physical quenching is not neghgible. The rate constants of O2 toward the main reactive amino acids that show a strong solvent dependence are reported in Table 2 for neutral aqueous solutions with values within the range 0.8-3.7... 

When RNase-S was treated with iodoacetate at pH 6, both inactivation and histidine modification occurred 164). The modified histidine was in S-protein and was assumed to be His 119 since the sole product on analysis was 1-CM-His. In the absence of S-peptide only methionine modification occurred in S-protein. The loss of potential activity probably resulted from the reaction of the second of the two modifiable Met residues. The location of these residues in the sequence was not established. 

Perhaps the most obvious approach to the synthesis of heme protein models is to reproduce the local environment of the heme active site by covalently attaching various peptide fragments to a suitable porphyrin. If the peptide fragments contain suitable amino acids (e.g. histidine, methionine), reproduction of the coordination sphere of the heme protein may be possible. 

Aqueous ozonation of the 22 most common amino acids and some small peptides was studied through electrospray mass (ESI-MS) and tandem mass spectrometry by Eberlin and coworkers [77]. After 5 min of ozonation, only histidine, methionine, tryptophane, and tyrosine formed oxidation products clearly detectable by ESI-MS (Scheme 5.20). 

D.xi.a. Hydrolysis and Hydration. The electrophilicity of cationic palladium(II) complexes has been taken advantage of in an interesting biomimetic method of selective cleavage of peptide bonds at histidine, methionine, or tryptophane residues. Further discrimination is possible as peptides with two former amino acids are cleaved in aqueous solution but not cleaved in acetone, while those with tryptophane are cleaved only in acetone in the presence of water. The mechanism of cleavage at tryptophane is particularly interesting as it involves the electrophilic ip o-paUadation of indole ring, while the remaining coordination site of Pd in the ip/ro-cyclopalladated complex is used for the electrophilic activation of carbonyl (Scheme 91). 

Absorption readings at 280 nm are used for the determination of proteins and peptides. Histidine, cysteine and methionine absorb between 200 and 210 nm. 

Mel, CH3CN morpholine or diethylamine, methanol, 76-95% yield. These conditions also cleave tlie 4 -pyridyl derivative. The Pet ester is stable to the acidic conditions required to remove the BOC and r-butyl ester groups, to the basic conditions required to remove the Fmoc and Fm groups, and to hydrogenolysis. It is not recommended for use in peptides that contain methionine or histidine since these are susceptible to alkylation with methyl iodide. 

Kentolysin Compared to Heliantholysin. Stoichactis helianthus occurs in the Caribbean region whereas another species, Stoichactis kenti is distributed in the Indo-Pacific area. The latter produces a toxin, kentolysin, that is similar to, but not identical with heliantholysin (6). The amino acid compositions of the two polypeptides show a distinct resemblance but appear to differ significantly in number of residues of lysine, methionine, tyrosine and histidine. IgG from a rabbit immunized against heliantholysin neutralizes both heliantholysin and kentolysin, but neutralization of the homologous toxin is more efficient (Table III). It can be seen that in the concentrations used, the IgG failed to neutralize the related lytic peptides of Condylactis gigantea and Epiactis prolifera. 

Selective cleavage of peptides and proteins is an important procedure in biochemistry and molecular biology. The half-life for the uncatalyzed hydrolysis of amide bonds is 350 500 years at room temperature and pH 4 8. Clearly, efficient methods of cleavage are needed. Despite their great catalytic power and selectivity to sequence, proteinases have some disadvantages. Peptides 420,423,424,426 an(j proteins428 429 can be hydrolytically cleaved near histidine and methionine residues with several palladium(II) aqua complexes, often with catalytic turnover. 

Figure 2.5 The cisplatin reactive group can covalently couple to methionine-, cysteine-, and histidine-containing peptides or proteins. It also reacts with guanine groups to form a covalent modification on the N7 nitrogen.

The LFMM FF for the oxidized Cu(II) centers was designed around suitable homoleptic species, viz., [Cu(imidazole)4]2+, [Cu(SCH3)4]2-, [Cu(S(CH3)2)4]2+, and [Cu(0=CH2)4]2+ (37). These complexes represent models for Cu-histidine, Cu-cysteine, Cu-methionine, and Cu-glutamine O/peptide respectively. Only the first of these species is known experimentally. However, it is amply documented that DFT gives excellent structures for metal complexes (64,65) so we can access the remaining species computationally (Fig. 20). 

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