Tags

Type your tag names separated by a space and hit enter

In vitro conversion of formate to serine: effect of tetrahydropteroylpolyglutamates and serine hydroxymethyltransferase on the rate of 10-formyltetrahydrofolate synthetase.
Biochemistry. 1989 Nov 28; 28(24):9430-9.B

Abstract

Serine hydroxymethyltransferase and C1-tetrahydrofolate synthase catalyze four reactions which convert formate and glycine to serine. The one-carbon carrier in these reactions if tetrahydropteroylglutamate which is regenerated in the coupled reaction and thus can be used in catalytic concentrations with respect to serine synthesis. The rate of serine synthesis is followed by the oxidation of NADPH during reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. Km values for the substrates of cytosolic serine hydroxymethyltransferase and the 10-formyltetrahydrofolate synthetase activity of the trifunctional enzyme C1-tetrahydrofolate synthase were determined. This included the values for the polyglutamate forms of tetrahydropteroylglutamate containing from one to six glutamate residues. The results suggest that the synthetase active site binds the polyglutamate forms of the coenzyme synergistically with respect to formate and ATP. Using saturating levels of all substrates, the kcat values for the serine hydroxymethyltransferase and 10-formyltetrahydrofolate synthetase activities were also determined. The synthetase reaction is the rate-determining step in the conversion of formate to serine. The effect of glutamate chain length and the concentration of serine hydroxymethyltransferase were studied with respect to the rate of serine formation. Tetrahydropteroylmonoglutamate gave slower than expected rates which is attributed to its inhibition of the reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. This inhibition was not a factor with the di- through hexaglutamate forms of the coenzyme. The addition of an excess of serine hydroxymethyltransferase was predicted to lower the rate of the formation of serine by lowering the concentration of free coenzyme in the assay. However, activation of the rate was observed which was at least 2-fold greater than the predicted rate. This increase in predicted rate appears to result from an interaction between C1-tetrahydrofolate synthase and serine hydroxymethyltransferase. The in vivo concentrations of serine hydroxymethyltransferase and C1-tetrahydrofolate synthase in rabbit liver were determined.

Authors+Show Affiliations

Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond 23298.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

2514800

Citation

Strong, W B., and V Schirch. "In Vitro Conversion of Formate to Serine: Effect of Tetrahydropteroylpolyglutamates and Serine Hydroxymethyltransferase On the Rate of 10-formyltetrahydrofolate Synthetase." Biochemistry, vol. 28, no. 24, 1989, pp. 9430-9.
Strong WB, Schirch V. In vitro conversion of formate to serine: effect of tetrahydropteroylpolyglutamates and serine hydroxymethyltransferase on the rate of 10-formyltetrahydrofolate synthetase. Biochemistry. 1989;28(24):9430-9.
Strong, W. B., & Schirch, V. (1989). In vitro conversion of formate to serine: effect of tetrahydropteroylpolyglutamates and serine hydroxymethyltransferase on the rate of 10-formyltetrahydrofolate synthetase. Biochemistry, 28(24), 9430-9.
Strong WB, Schirch V. In Vitro Conversion of Formate to Serine: Effect of Tetrahydropteroylpolyglutamates and Serine Hydroxymethyltransferase On the Rate of 10-formyltetrahydrofolate Synthetase. Biochemistry. 1989 Nov 28;28(24):9430-9. PubMed PMID: 2514800.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - In vitro conversion of formate to serine: effect of tetrahydropteroylpolyglutamates and serine hydroxymethyltransferase on the rate of 10-formyltetrahydrofolate synthetase. AU - Strong,W B, AU - Schirch,V, PY - 1989/11/28/pubmed PY - 1989/11/28/medline PY - 1989/11/28/entrez SP - 9430 EP - 9 JF - Biochemistry JO - Biochemistry VL - 28 IS - 24 N2 - Serine hydroxymethyltransferase and C1-tetrahydrofolate synthase catalyze four reactions which convert formate and glycine to serine. The one-carbon carrier in these reactions if tetrahydropteroylglutamate which is regenerated in the coupled reaction and thus can be used in catalytic concentrations with respect to serine synthesis. The rate of serine synthesis is followed by the oxidation of NADPH during reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. Km values for the substrates of cytosolic serine hydroxymethyltransferase and the 10-formyltetrahydrofolate synthetase activity of the trifunctional enzyme C1-tetrahydrofolate synthase were determined. This included the values for the polyglutamate forms of tetrahydropteroylglutamate containing from one to six glutamate residues. The results suggest that the synthetase active site binds the polyglutamate forms of the coenzyme synergistically with respect to formate and ATP. Using saturating levels of all substrates, the kcat values for the serine hydroxymethyltransferase and 10-formyltetrahydrofolate synthetase activities were also determined. The synthetase reaction is the rate-determining step in the conversion of formate to serine. The effect of glutamate chain length and the concentration of serine hydroxymethyltransferase were studied with respect to the rate of serine formation. Tetrahydropteroylmonoglutamate gave slower than expected rates which is attributed to its inhibition of the reduction of the intermediate 5,10-methenyltetrahydropteroylglutamate. This inhibition was not a factor with the di- through hexaglutamate forms of the coenzyme. The addition of an excess of serine hydroxymethyltransferase was predicted to lower the rate of the formation of serine by lowering the concentration of free coenzyme in the assay. However, activation of the rate was observed which was at least 2-fold greater than the predicted rate. This increase in predicted rate appears to result from an interaction between C1-tetrahydrofolate synthase and serine hydroxymethyltransferase. The in vivo concentrations of serine hydroxymethyltransferase and C1-tetrahydrofolate synthase in rabbit liver were determined. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/2514800/In_vitro_conversion_of_formate_to_serine:_effect_of_tetrahydropteroylpolyglutamates_and_serine_hydroxymethyltransferase_on_the_rate_of_10_formyltetrahydrofolate_synthetase_ DB - PRIME DP - Unbound Medicine ER -