Mutant aminopeptidases of Pisum sativum. I. Developmental genetics and chemical characteristics

Summary Two forms of aminopeptidase (AmP) were found, by conventional zone electrophoresis, to be present in all tissues at various stages of normal development and differentiation of Pisum sativum. One of the enzymes (AmP-1) proved to be polymorphic, with alternate electrophoretic forms existing in different inbred pea strains, while the other enzyme (AmP-2) was found to be monomorphic. The AmP-1 variants are under the control of two codominant alleles (AmP-1^F and AmP-1^S) at the AmP-1 locus. The AmP-2 enzyme is most likely controlled by a separate genetic locus. Substrate specificity studies, using various -amino acid naphthylamides as substrates, showed that the aminopeptidases of Pisum are not specific for leucine N-terminal residues. The AmP-1 and AmP-2 enzymes behaved quite differently with respect to substrate specificity and metal ion inhibition, suggesting differences in the biological function and relatedness of the two enzymes.This investigation was supported by the U.S. Atomic Energy Commission under Contract No. AT(11-1)1338.