Supplemental methionine in a complete culture medium increased the methionine content of the protein fraction of cultured soybean (Glycine max L. Merrill) cotyledons (Thompson, Madison, Muenster 1981 Phytochemistry 20: 941-945). To explain the observed increase in protein methionine, we have measured the amounts and subunit compositions of 7S and 11S storage proteins and determined the amino ac...

1. Hepatic levels of cystathionine synthase and methionine-activating enzyme are significantly lower in rats fed a diet low in methionine and supplemented with cystine than in rats growing at the same rate while maintained on a diet adequate in methionine, with or without cystine supplementation. Cystathionase levels are also decreased, but to a smaller extent. Betaine-homocysteine methyltransf...

The preparation, purification, and analysis of a variety of new sulfonium derivatives of methionine is reported. Deamination of S-adenosyl-L-methionine with nitrous acid yielded, depending on experimental conditions, S-adenosyl L-(Z-hydroxy-4-methylthio)butyric acid or S-inosyl-L-(Z-hydroxy 4 methylthio)butyric acid. S-Inosyl L methionine was obtained by enzymatic deamination of S-adenosyl-Lhom...

The two tripeptide antibiotics L-2-amino-4-methylphosphinobutyryl-alanyl-alanyl-alanine (L-phosphinothricyl-alanyl-alanine) and L-(N5-phosphono)methionine-S-sulfoximinyl-alanyl-alanine, both inhibitors of the glutamine synthetase, are transported into the cell of Escherichia coli K 12 via the oligopeptide transport system. The uptake by this system is proved first of all by cross-resistance wit...

The transamination of 7-keto-8-aminopelargonic acid by 7, 8-diaminopelargonic acid aminotransferase of Escherichia coli requires S-adenosyl-L-methionine as the amino donor. Initial velocity studies of this reaction revealed a parallel pattern of reciprocal plots characteristic of a ping-pong mechanism. m-Keto-8-aminopelargonic acid showed strong substrate inhibition which was competitive with S...

The binding interactions of cucurbit[8]uril (Q[8]) with l -valine, d -leucine, and -methionine, both in aqueous solution solid state, have been studied by 1 H NMR spectroscopy X-ray crystallography.

The irreversible inhibition of glutamine synthetase by methionine sulfoximine is associated with the tight binding to the enzyme of adenosine diphosphate and methionine sulfoximine phosphate; the latter compound can be cleaved nonenzymatically and also by phosphatases to equimolar amounts of methionine sulfoximine and inorganic phosphate. Methionine sulfoximine phosphate is oxidized by L-amino ...

It is generally recognized that formate is converted to a compound which is utilized in the synthesis of serine (l-3), purines (4, 5), and labile methyl groups (6-8) in animal tissues. Futhermore, compounds which, in the course of their metabolism, form a lrCl compound”l similar to the one formed from formate likewise serve as precursors in the synthetic reactions mentioned above (cf. (9, 10))....

Glutamate synthase, isolated in apparently homogeneous form (Mr approximately 265,000) from Saccharomyces cerevisiae after 7500-fold purification, is markedly inhibited by homocysteine sulfonamide. Inhibitions competitive with respect to L-glutamine; the apparent Ki value calculated for L-homocysteine sulfonamide is 3.6 microM; the apparent Km value for L-glutamine is 280 microM. The very high ...

The half-lives of 35S-labelled L-methionine and of 3H-labelled L-fucose of serum transferrin of rats were measured in pulse-chase experiments in vivo. Both L-[35S]methionine and L-[6-3H]fucose disappeared from transferrin with nearly the same half-lives of 33.8 h and 36.5 h, respectively. The data show that in this major serum glycoprotein peripheral carbohydrates and the protein moiety are deg...