5-Adenosylmethionine, from methionine

Adenosine triphosphate, coupled reactions and. 1128-1129 function of, 157, 1127-1128 reaction with glucose, 1129 structure of, 157, 1044 S-Adenosylmethionine, from methionine, 669 function of, 382-383 stereochemistry of, 315 structure of, 1045 Adipic acid, structure of, 753 ADP, sec Adenosine diphosphate Adrenaline, biosynthesis of, 382-383 molecular model of, 323 slructure of, 24... 

The methyl transfer from methionine has been reported to depend on the formation of S-adenosylmethionine from methionine and ATP. 

The formation of this complex cofactor occurs in one of only two known reactions in which triphosphate is cleaved from ATP (Fig. 3) the other reaction is the formation of S-adenosylmethionine from ATP and methionine (see Fig. 18-18). 

Step (v), conversion of [Fe(NO)2(SMe)2] to the product [Fe2(SMe)2(NO)4], occurs spontaneously under the appropriate conditions of solvent polarity/polarizability (23) [cf. Eq. (20) and Schemes 3 and 4], Step(vi) requires the methylation of [Fe2S2(NO)4]2 " while this has been demonstrated for methylation by methyl halides (3, 24, 29), methylation by biological methyl transfer, e.g., from methionine or S-adenosylmethionine, has yet to be investigated. Thus, although neither of the biosynthetic routes suggested in Scheme 5 has yet been fully investigated, several of the steps [(i), (ii), and (vi)], are established, while others [(iv) and (vi)] are already known to occur under nonbiological conditions. 

Methionine is the major precursor in the biochemical pathway to ethylene (9). Ethylene is formed from carbons 3 and 4 of methionine which is degraded in reactions possibly involving free radicals and oxygen (9). Recently Adams and Yang (10,11) identified S-adenosylmethionine (SAM) and 1-aminocyclopropane-l-carboxylic acid (ACC) as intermediates in the pathway from methionine to ethylene. The sequence of reactions in the pathway... 

Most methyltransferase reactions use methionine as the source of methyl groups. The actual methyl donor is S-adenosyl methionine, abbreviated S-AdoMet, or more colloquially, SAM. S-Adenosylmethionine is made from methionine and ATP. Note how the reaction consumes all three high-energy phosphate bonds of the ATP as shown in Figure 5-5. 

S-Adenosylmethionine (SAM), which is produced from methionine and ATP, is involved in the transfer of methyl groups to compounds such as creatine, phosphatidylcholine, epinephrine, melatonin, and methylated polynucleotides. 

One of the major methylating agents in biological systems is 5-adenosylmethionine. Its biosynthesis, from methionine and ATP, is catalysed by 5-adenosyl synthase. In the first... 

S-ADENOSYLMETHIONINE S-Adenosylmethionine (SAM) is the major methyl group donor in one-carbon metabolism. Formed from methionine and ATP (Figure 14.16), SAM contains an activated methyl thioether group, which can be transferred to a variety of acceptor molecules (Table 14.3). S-Adenosylhomocysteine... 

The mode of formation of a methyl group seen in thymidylate is exceptional most methyl groups in biological molecules arise from the S-methyl group of methionine. Our next goal was to determine the steric course of the transfer of a methyl group from methionine or S -adenosylmethionine (AdoMet) to various C-, N-, or... 

Pathways of caffeine metabolism are described and discussed by Waller and Suzuki (1990). One methyl source is 5-adenosylmethionine synthesized from methionine. In Coffea arabica, caffeine is synthesized in the pericarp and transported to the seeds where it accumulates. 

S-adenosylmethionine (SAM) SAM, produced from methionine and adenosine triphosphate (ATP), transfers the methyl group to precursors forming a number of compounds, including creatine, phosphatidylcholine, epinephrine, melatonin, methylated nucleotides, and methylated DNA. 

How many high-energy bonds are expended during the synthesis of S-adenosylmethionine from ATP and methionine ... 

C4H,N02,Mr 101.1 l,mp. 229-231 °C. A non-proteinogenic amino acid first known as a synthetic product and later isolated from pears and apples. ACC is formed from methionine via 5-adenosylmethionine with the help of ACC synthase (EC 4.4.1.14) and cleaved by ACC oxidase to the multifunctional plant growth substance ethylene which plays key roles in various plant physiological processes such as ripening of fruit, aging, germination, and response to stress. 

Biosynthesis Formed from methionine and L-serine through 5-adenosylmethionine, 5-adenosylhomocys-teine, and homocysteine (C4H,NOaS, Mr 135.18, mp. 233 °C). 

Among these polyamines, putrescine is biosynthesized from ornithine by decarboxylation with ornithine decarboxylase. Putrescine receives a propyl-amino rmit (C3N unit) from decarboxylated SAM (S-adenosylmethionine) to form spermidine. SAM is derived from methionine. Spermidine synthase catalyzes this biosynthetic process. Spermine is formed from spermidine through the addition of a C3N unit from a decarboxylated SAM unit under the catalysis of spermine synthase [3]. 

The transfer of the methyl group from methionine to these other compounds does not take place directly. The actual methylating agent is not methionine it is S-adenosylmethionine, a compound that results when methionine reacts with adenosine triphosphate (ATP) ... 

Adenosylmethionine is an important methyl group donor for many biosynthetic methylation reactions in plants (Cossins, 1980, 1987). It is formed from methionine according to the reaction... 

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