The Biosynthesis of Folic Acid Compounds in Plants1 I. Enzymatic Formation of Dihydropteroic Acid and Dihydrofolic Acid from 2-Amino-4-hydroxy-6-substituted Pteridines by Cell-free Extracts of Pea Seedlings2
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چکیده
pteroic acid and dihydrofolic acid from p-aminobenzoic acid and p-aminobenzoylglutamic acid, respectively, in the presence of pyrophosphorylmethyldihydropteridine. In the enzymatic reaction, p-aminobenzoic acid was more active as substrate than p-amino benzoylglutamic acid. When p-aminobenzoic acid and L-glutamic acid were used in place of p-aminobenzoic acid in the enzyme system, dihydropteroic acid and dihydrofolic acid were formed in the presence of the pteridine, ATP and Mg2+. From these results
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The Biosynthesis of Folic Acid. v. Characteristics of the Enzyme System That Catalyzes the Synthesis of Dihydropteroic Acid.
Although p-aminobenzoylglutamic acid can be used as substrate in place of p-aminobenzoic acid to yield dihydrofolic acid directly, dihydropteroic acid is thought to be an intermediate (as shown above) rather than p-aminobenzoylglutamic acid, because paminobenzoic acid is utilized as substrate at least 10 times more effectively than p-aminobenzoylglutamic acid (2). The formulation of the dihydro...
متن کاملThe Biosynthesis of Folic Acid. Iii. Enzymatic Formation of Dihydrofolic Acid from Dihydropteroic Acid and of Tetrahydropteroylpolyglutamic Acid Compounds from Tetrahydrofolic Acid.
Although dihydrofolic acid can be formed enzymatically, in the presence of adenosine triphosphate, from 2-amino4-hydroxy-6hydroxymethyldihydropteridine and p-aminobenzoylglutamic acid (3, 4), Brown, Weisman, and Molnar (4) have postulated that dihydropteroic acid, instead of p-aminobenzoylglutamic acid, is the normal intermediate in dihydrofolate synthesis in Escherichia coli. They have present...
متن کاملThe Biosynthesis of Folic Acid I. SUBSTRATE AND COFACTOR REQUIREMENTS FOR ENZYMATIC SYNTHESIS BY CELL-FREE EXTRACTS OF ESCHERICHIA COLI*
The formation of folic acid compounds from pteridines and p-aminobenzoic acid by whole bacterial cells has been studied by Korte et al. (1, 2), who reported that C%xanthopterin (2-amino4,6-dihydroxypteridine) could be incorporated into folic acid by several bacterial species, and by Weygand et al. (3), who found that certain strains of bacteria can be adapted to utilize 2.amino-4-hydroxy-6-form...
متن کاملThe Biosynthesis of Folic Acid
The biological importance of p-aminobenzoic acid was recognized only in 1940 when Woods showed that the compound antagonized the bacteriostatic effects of sulfonamides (2). Later, p-aminobenzoic acid was found to be an essential part of the folic acid molecule (3, 4), and it now seems quite likely that the sole metabolic function of p-aminobenzoate is to serve as a precursor for the biosynthesi...
متن کاملEnzymatic synthesis of the pteridine moiety of dihydrofolate from guanine nucleotides.
Much of the knowledge of pteridine biosynthesis from purines has come from radioactive tracer studies with whole organisms. Reports on the incorporation of the radioactivity of labeled precursors of purines (1) and of uniformly labeled adenine-1% (2) into riboflavin indicated the utilization of purines for riboflavin synthesis. Furthermore, the results of studies (2, 3) with adenine-814C showed...
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