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S-Adenosylmethione

Type I restriction enzymes, such as those encoded in the chromosome of E. coli, are large 300- to 400-kDa proteins composed of at least three kinds of polypeptide chain. They bind at specific sites of a foreign DNA and apparently cleave the chain randomly nearby. They require ATP, Mg2+, and S-adenosylmethion-ine and have the unusual property of promoting the hydrolysis of large amounts of ATP.81 82 The significance of these properties is still unknown. [Pg.1486]

Xanthosine, which is derived from purine metabolites, is the first committed intermediate in caffeine biosynthesis (Fig. 4). Xanthosine can be formed from de novo purine biosynthesis, S-adenosylmethione (SAM) cofactor, the adenylate pool, and the guanylate pool (169). De novo purine biosynthesis and the... [Pg.10]

Once SAM (S-adenosylmethion-ine) donates its methyl group, it must be regenerated by reactions that require the vitamins folate and B,2. Thus formation of mRNA is also one of the processes affected by a deficiency of these vitamins. [Pg.245]

Impressively, the model hypothesized a positive methyl group long before such a methyl donor had been identified. Today we know that S -adenosylmethione (SAM, also known as AdoMet) is the most important such donor, and glutathione and other cellular thiols are the key reducing agents ... [Pg.169]

The compounds that are the immediate methyl gronp donors are methyltetra hydrofate (CH3-FH4) and S-adenosyl methionine (SAM) (see Figure 15.2). These are involved in, at least, five key reactions or processes which are summarised in Figure 15.4. Complexity arises in the topic of methyl group transfer in formation and reformation of the methylating compounds 5-adenosylmethione and methyl tetrahydrofolate. There are four important reactions in the formation utilisation and then the reformation of 5-adenosylmethionine as follows ... [Pg.335]


See other pages where S-Adenosylmethione is mentioned: [Pg.256]    [Pg.1462]    [Pg.355]    [Pg.226]    [Pg.549]    [Pg.528]    [Pg.256]    [Pg.1462]    [Pg.355]    [Pg.226]    [Pg.549]    [Pg.528]    [Pg.693]   
See also in sourсe #XX -- [ Pg.296 , Pg.329 ]




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