Isoleucine and Valine Metabolism of Escherichia coli XIV. Effect of Thiaisoleucine

Abstract

Thiaisoleucine (2-amino-3-methylthiobutyrate) completely inhibited the growth of strain K-12 of Escherichia coli at a concentration of 5 × 10 −3 m . The inhibition was antagonized by growth-factor amounts of l -isoleucine. Thiaisoleucine inhibited the deamination of threonine and the transfer of 14 C-isoleucine to soluble ribonucleic acid and underwent transamination with α-ketoglutarate as the amino acceptor. In each case, the analogue appeared to be less effective than isoleucine as either an inhibitor or substrate.