Folylpolyglutamate synthase

The data in Table 9.1 are from an experiment involving folylpolyglutamate synthase. The enzyme was obtained in purified form from liver and was mixed with glutamic acid, ATP, and the indicated form of folate. The mixture was incubated to permit the enzyme to catalyze the attachment of glutamate residues to the folate. What do you think would be the effect of a vitamin B12 deficiency on the rate of polyglutamation of dietary folates. Hint Dietary folates occur in the bloodstream initially as 5-methyl-H4PteGlu, and enter the cell in this form. 

The three-dimensional structure of folylpolyglutamate synthase of Lactobacillus casei and E. coli have been determined by X-ray crystallography. The catalytically active conformation of the protein is obtained by bonding of a folate-type substrate binding of ATP is not, perse, sufficient to generate that conformational state. 

Figure 2 Biosynthesis of foiates. a, GTP cyclohydrolase I b, dihydroneopterin epimerase c, nudix hydrolase d, phosphatase e, dihydroneopterin aldolase f, hydroxymethyidihydropterin pyrophosphokinase g, dihydropteroate synthase h, dihydrofolate synthetase I, dihydrofolate reductase j, folylpolyglutamate synthetase k, aminodeoxychorismate synthase I, aminodeoxychorismate lyase. 7, 7,8-dihydro-D-neopterin 3 -triphosphate 8, 7,8-dihydro-L-monapterin 3 -triphosphate 9, 7,8-dihydro-D-neopterin 3 -monophosphate 10, 7,8-dihydro-D-neopterin 11, glycolaldehyde ...

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