Primary structure and tetrahydropteroylglutamate binding site of rabbit liver cytosolic 5,10-methenyltetrahydrofolate synthetase. Academic Article uri icon

abstract

  • The primary sequence of 5,10-methenyltetrahydrofolate synthetase from rabbit liver was determined by amino acid sequencing of the purified enzyme. The enzyme contains 201 amino acid residues with a predicted mass of 22,779 Da. The enzyme is located in the cytosolic fraction of liver homogenates. Carbodiimide-activated 5-formyltetrahydropteroylmonoglutamate and the pentaglutamate form of the substrate both irreversibly inactivate the enzyme by forming a covalent bond to Lys-18. Non-activated 5-formyltetrahydropteroylpentaglutamate protected against this inactivation. Substrate specificity studies showed that increasing the number of glutamate residues from zero to five on 5-formyltetrahydropteroate results in a 2 order of magnitude increase in the affinity of the substrate for the enzyme but only a 3-fold increase in the value of Vmax.

published proceedings

  • J Biol Chem

citation count

  • 29

complete list of authors

  • Maras, B||Stover, P||Valiante, S||Barra, D||Schirch, V

publication date

  • July 1994