title: On the cofactor specificity of glycinamide ribonucleotide and 5-aminoimidazole-4-carboxamide ribonucleotide transformylase from chicken liver.
abstract: Tests of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) and glycinamide ribonucleotide (GAR) transformylase cofactor specificity were conducted with 5-and/or 8-deazafolate analogues formylated at N-10. Several of these compounds were found to serve as cofactors for both the enzymes. The finding that 10-formyl-8-deazafolate can be used by AICAR transformylase eliminates those mechanisms requiring cyclization to a methenyl derivative prior to carbon unit transfer for this transformylase. Surprisingly, a similar analogue, 10-formyl-5,8-deazafolate, is very effective as a cofactor for GAR transformylase in the presence or absence of the trifunctional protein which is required for 5,10-methenyl-H4-folate activity with this transformylase. This finding suggests that the trifunctional protein modulates GAR transformylase cofactor specificity by supplying the active cofactor as the N10-formyl species, possibly through a transport process that avoids its dissociation into solution.
mesh_terms: D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D002645:Chickens; D005493:Folic Acid Antagonists / Q000138:chemical synthesis / Q000494:pharmacology*; D005561:Formates / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives / Q000378:metabolism; D019877:Hydroxymethyl and Formyl Transferases; D008099:Liver / Q000201:enzymology*; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D051026:Phosphoribosylglycinamide Formyltransferase; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D005493:Folic Acid Antagonists; D005561:Formates; D019877:Hydroxymethyl and Formyl Transferases; D051026:Phosphoribosylglycinamide Formyltransferase; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D000217:Acyltransferases; D005998:Glycine