The synthesis of pteroylpolyglutamates by sheep liver enzymes in vitro

Abstract

1. Sephadex G-15 was used to separate pteroylmonoglutamates from corresponding polyglutamate derivatives. 2. Pteroylpolyglutamates were formed when 5-formyltetrahydro[2-¹⁴C]pteroylglutamic acid, 5-[methyl-¹⁴C]tetrahydropteroylglutamic acid or tetrahydro[2-¹⁴C]pteroylglutamic acid was incubated at pH8.4 with ATP, MgCl₂, KCl, l-glutamic acid and sheep liver cytosol. The γ-glutamyl side chain appeared to be lengthened by the stepwise addition of single glutamate moieties. 3. The subcellular distribution of pteroylpolyglutamates paralleled that of pteroylpolyglutamate synthetase activity, and followed the order cytosol>‘nuclear’ fraction>microsomal fraction>mitochondria.