Methionines methyl

The biosynthesis of two major classes of red tide toxins, saxitoxin analogs and brevetoxins, have been studied. It was shown that saxitoxin is biosynthesized from arginine, acetate, and methionine methyl group. Brevetoxins were shown to be unique polyketides, which are probably biosynthesized from dicarboxylic acids. Some details of the biosynthetic mechanism have been elucidated. 

The result is not totally surprising, because hydride ion shifts are known in many methylations. Thus, it was proposed that the methyl carbinol is formed by the sequence methylation of a double bond - hydride shift - formation of terminal methylene - epoxidation - opening of the epoxide to aldehyde - reduction to carbinol (Scheme 6). The pathway can explain well the loss of two original hydrogens in methionine methyl group. 

Several cationic palladium(II) aqua complexes, [Pd(H20)4], cis-[PdL(H20)2] (L = en, methionine methyl ester, l,5-dithiacycloocta-3-ol), and [Pd(dien)(H20)], serve as the active catalyst for the selective hydration of various nitriles to the corresponding carboxamides, e.g., CHCI2CN was hydrated to CHCl2C(0)NH2 in the presence of... 

Methionine Methyl mercaptan (s) Dimethyl sulfide (m) Dimethyl disulfide (1)... 

Scheme T. Synthesis of Olefin Isosteres of CaaX Analogues, a) (CH3)2C= CHMgBr b) NaBH4 c) Ac20 d) O3, (CH3)2S e) Ph3P=CHC02 CH3 fl LiOH g) EDC, HOBt, L-methionine methyl ester h) CH3S02Cl /) R2MgCuCNCI-BF3 j) HCI L-N-Boc-S-tritylcysteine aldehyde, NaCNBH3 k) TFA, (QHshSiH I) NaOH.

S-Adenosyl methionine Methyl group Bacteria, archaea and eukaryotes ... 

Cullen et al. (1994) have proposed a possible mechanism of arsenic methylation after the study in which arsenite, arsenate, monomethyl-arsonate or dimethylarsinic acid were added to the growth medium in the presence of the unicellular alga Polyphsa peniculus. Evidence of arsenic biomethylation by the micro-organism Apiotrichum humicola in the presence of L-methionine-methyl-d3 has come from the same laboratory (Cullen et al., 1995). Their findings point to the role of S-adenosylmethionine, or a related sulfonium compound as possible methyl donors. Arsenic biomethylation and biotransformation has also been demonstrated in a freshwater environment (Kuroiwa et al., 1994). 

Cullen, W.R., Li, H., Pergantis, S.A., Eigendorf, G.K. and Mosi, A A. (1995) Arsenic biomethylation by the microorganism Apiotrichum humicola in the presence of L-methionine-methyl d3. Appl. Organomet. Chem., 9, 507-515. 

After some days in trifluoroacetic acid solution at 5°, the spectra of pepsin and bovine hemoglobin (not shown) exhibit a much more prominent peak in the methionine methyl position. This effect is probably the result of additional rotational freedom, brought about by cleavage of some of the peptide bonds. 

One-electron oxidation mechanism of methionine methyl ester (MME), N-acetylmethionine (NAM), N-acetylmethionine amide (NAMA), and N-acetylmethionine methyl ester (NAMME) employing OH radicals were studied by means of pulse radiolysis in aqueous solutions. 

Shirdhonkar M, Maity DK, Mohan H, Rao BSM. (2006) Oxidation of methionine methyl ester in aqueous solution A combined pulse radiolysis and quantum chemical study. Chem Phys Lett API 116-123. 

PAME = phenylalanine methyl ester, MME = methionine methyl ester, PME = proline methyl ester, DMPEA = A,a-dimethyl-j3-phenylethylamine. 

After hydrolysis is complete the tubes are cooled, scored and opened, and the acid is removed, either by rotary evaporation or in a heated desiccator over NaOH at 40-50°C. In our laboratory it is standard procedure to examine 1/10 of each hydrolysate by high-voltage paper electrophoresis at pH 1.9 (see Appendix I) prior to analysis to ensure that appropriate amounts are analyzed. Some amino acid derivatives (oxidation products of methionine, methylated lysines, etc.) are also sometimes observed by this procedure. It is usually helpful to add an internal standard, either prior to hydrolysis to reveal hydrolytic losses or prior to analysis to reveal analytical losses. For this purpose we have used norleucine (0.03 pmoles). This amino acid elutes after leucine on the 60 cm column. 

Muscle contraction is regulated, to a significant extent, by the interaction of troponin (Tn) proteins C, I and T. The interactions between Tn I and Tn C were studied by NMR using Tn C with a spin label attached to Cys84 and specifically 13C-labelled at its 10 methionine residues.208 From the known assignments of the methionine methyl cross-peaks in the HSQC spectrum of Tn C, and their absence from HSQC spectra in the presence of fragments of the bound Tn I, it was concluded that the linker between the two domains of Tn C is flexible, allowing association between the two domains in the presence of Tn 1. 

Protease mutants were prepared, which showed higher catalytic activity for the enzymatic polymerization of amino acid esters in an aqueous DMF solution. The molecular weight greatly increased by using a subtilisin mutant (subtilisin 8350) derived from BPN (subtilisin from Bacillus amyloliquefa-ciens) via six site-specific mutants (Met 50 Phe, Gly 169 Ala, Asn 76 Asp, Gin 206 Cys, Tyr 217 Lys, and Asp 218 Ser) in the polymerization of L-methionine methyl ester in the aqueous DMF.240 Another mutant (subtilisin 8397), which is the same as 8350 without... 

The reaction was applied to model dipeptides exemplified by the y-phenyl-hydrazide of N-carbobenzoxy-a-L-glutamyl-L-methionine methyl ester (4) and found to afford the carboxylic acid (S) in good yield without disturbance of the carbo-benzoxy and ester protective groups. The results suggest use of the phenylhydrazide group for protection of carboxyl groups in peptide chemistry. 

Fosfomycin, a clinically used antibiotic, is biosynthetically derived from a P C unit, probably phosphonoacetaldehyde, and an L-methionine methyl group (Scheme 5.86). Phosphoenolpyruvate (PEP) is the most likely precursor of carbons 1 and 2 of fosfomycin. " ... 

L-Methionine methyl ester hydrochloride u-Methionine, methyl ester, hydrochloride (2491-18-1), 76, 123... 

A. N-(Benzyloxycarbonyl)-L-wethionine methyl ester 2). A 3-L, three-necked, Morton flask equipped with an efficient mechanical stirrer, thermometer, and a dropping funnel is charged with L-methionine methyl ester hydrochloride (117.6 g,... 

Akutsu H, Park J-S, Sano S (1993) L-Methionine methyl is specifically incorporated into the C-2 and C-7 positions of the porphyrin of cytochrome c3 in a strictly anaerobic bacterium, Desul-fovibrio vulgaris. J Am Chem Soc 115 12185-12186... 

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