THREONINE DEAMINATION IN ESCHERICHIA COLI II

Open Access
Publisher Website
Google Scholar
Abstract
Isoleucineless mutants of E. coli which can use alpha- ketobutyrate as a growth factor are deficient in their capacity to form the biosynthetic L-threonine deaminase. Using crude cell-free extracts, this enzyme appears to be quite distinct from the adaptive L-threonine diamine of Wood and Gunsalus. The adaptive enzyme requires pyridoxal phosphate, adenosine-5-phosphate and glutathione as cofactors. The biosynthetic enzyme is strongly inhibited by L-isoleucine and requires only pyridoxal phosphate. The enzyme of Wood and Gunsalus is not affected by the mutation in isoleucineless mutants. Both enzymes are active against L-serine.