5 -Methyl-thioadenosine

Porcelli M, Cacdapuoti G, Cimino G, Gavagnin M, Sodano G, Zappia V (1988) Characterization and biogenesis of 5 -methylthioixylofuranosyIadenine, a new natural analog of 5 -methyl-thioadenosine. In Zappia V, Pegg AE (eds) Progress in polyamine research, Plenum, New York, p 219... 

The second nitrogen of biotin is incorporated by tremsamination of keto-tuninopeltirgonic acid, with S-adenosyhnethionine - an apparently unique metabolic role for this amino acid derivative that is normally a methyl donor. The immediate product of the detunination of S-adenosylmethionine, S-adenosyl-2-oxo-4-methylthiobutyric acid, is unstable and decomposes non-enzymictdly to 2-oxo-3-butenoic acid and 5 -methyl thioadenosine. 

Bacchi, C. J., Sufrin, J., Nathan, H. C. et al. (1991) 5 -Alkyl-substituted analogs of 5 -methyl-thioadenosine as trypanocides. Antimicrob. Agents Chemother. 35 1315-1320. 

In the nonprotein fraction reduced glutathione, GSH, is ubiquitous, and is commonly a mqjor constituent (Table I). The soluble fraction of plants also includes a variety of other sulfur-containing compounds that are normally present in relatively small amounts (a) Intermediates on the route to protein cysteine and protein methionine, such as cysteine, cystathionine, homocysteine, and methionine, (b) Compounds involved in methyl transfer reactions and polyamine synthesis AdoMet.t AdoHcy, and, presumably, 5 -methyl-thioadenosine. The biochemistry of the compounds in both groups (a) and (b) will be discussed here, (c) Compounds clearly related metabolically to cysteine or methionine, such as 5-methylcysteine and 5-methylmethionine. Because in certain plants these derivatives comprise a major portion of the nonprotein sulfur amino acids, they will be discussed here, (d) A number of compounds of uncertain function, the biochemistry of which has often not been clarified. Discussion of such compounds (Richmond, 1973 Fowden, 1964) is beyond the scope of this chapter. 

This enzyme [EC 3.2.2.16], also known as methylthioade-nosine nucleosidase, catalyzes the hydrolysis of methyl-thioadenosine to produce adenine and 5-methylthio-D-ribose. S-Adenosylhomocysteine is not a substrate for this enzyme. See also S-Adenosylhomocysteine Nucleosidase... 

Adenine thiomethylpentoside (5-iS-methyl-5-thioadenosine) (11b) was first isolated from yeast, but was thought to be present in the tissues of many animals. Hydrolysis of this nucleoside gave adenine and 5-S-methyl-... 

The reaction of 5-iodopropionic acid has been studied and its biological implications discussed. "... 

S-Ethyl-5-thioadenosine, isolated from extracts of yeast grown in the presence of DL-ethionine, behaves very similarly to the methyl compound. ... 

The deoxynucleoside problem was approached from another sequence, in which 3,5-di-O-benzoyl-D-arabinofuranosyl chloride was prepared, and then treated with sodium ethanethioxide to give, in a stereoselective reaction, ethyl 3,5-di-O-benzoyl-l-thio-a-D-arabinofuranoside, a thiogly-coside having the proper structure for neighboring-group transfer of the ethylthio group to C-2 by way of an episulfonium ion intermediate. This approach was later expanded in a successful synthesis of 2 -S-methyl-2 -thioadenosine and other derivatives of 2 -thioadenosine, all of which were potential precursors to 2 -deoxyadenosine. 

Methylthio)adenosine, M-134 5 -5-Methyl-5 -thioadenosine, T-52 2-(Methylthio)-5 -adenylic acid, M-133 2-(Methylthio)-AMP, M-133... 

Tetra-0-methyl-6-0-trityl-D-glucose dimethyl dithioacetal, G-516 2 -Thioadenosine 2 5,3 0-Isopropylidene, T-50 5 -Thioadenosine 5-Me, 2, 3 -0-isopropylidene, T-52 5 -Thioadenosine 5-Me, tritosyl, T-52... 

Cytidine 2, 3 -cyclicphosphate, polymeric complexes of Cd" and Cu" and cytidine 5 -phosphate, l-(j8-D-arabinofuranosyl)cytosine Pt complex. Adenosine complexed with 5-bromouracil, iS-methyl-5 -thioadenosine, 2, 3 -0-isopropyIideneadenosine, 2, 3 -0-(2-carboxyethyl)ethylideneadeno-sine, the amino-acid adenosine derivatives (5) and (6) which are constitutents of tRNA, 8-[(2-aminoethyl)amino]adenosine 3, 5 -cyclic phosphate. 8-Iodoguanosine, 2-JV-methylguanosine, a guanosine Hg" complex, 2, 35 -tri-(9-acetyl-6-0-(mesitylenesulphonyl)-guanosine, guanosine 5 -phosphate, Cu" complex. ... 

Putrescine, which is produced by decarboxylation of ornithine, and also arises from agmatine with catalysis by agmatinase, becomes the starting compound for the biosynthesis of spermidine and spermine. These reactions are catalysed by spermidine synthase and spermine synthase, respectively, involving S-adenosyl-L-methionine (for short AdoMet or SAM), and take place from bacteria to mammals (Figure 10.16). S-Adenosyl-L-methionine amide (dSAM) formed by decarboxylation of SAM provides trimethylene amine residue for this biosynthesis, which yields S-methyl-5 -thioadenosine (MTA). 

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