Purification and properties of two succinic semialdehyde dehydrogenases from Klebsiella pneumoniae

Two forms of succinic semialdehyde dehydrogenase have been isolated in Klebsiella pneumoniae M5a1. The two enzymes could be separated by filtration on Sephacryl S-300 and their apparent molecular weights were approx. 275,000 and 300,000. The large enzyme is specific for NADP. The smaller enzyme, which is induced by growth on 3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid, 3,4-dihydroxyphenylacetic acid and gamma-aminobutyrate, has been purified to 96% homogeneity by affinity chromatography. The NAD-linked succinic semialdehyde dehydrogenase was able to use NADP as cofactor. Its induction is coordinated with 3- and 4-hydroxylase, the enzymes which initiate degradation of 3- and 4-hydroxyphenylacetic acid. The NAD-linked form is also induced by exogenous succinic semialdehyde. The large enzyme is specific for NADP and has been isolated from a defective mutant which lacked the activity of the NAD-linked succinic semialdehyde dehydrogenase. Activity and stability conditions and true K m values for substrates and cosubstrates of the two enzymes were determined. Some aspects of the induction of the NAD-linked enzyme participating in the metabolism of 4-hydroxyphenylacetic and gamma-aminobutyrate were studied.