1887

Abstract

Summary: A dipeptidyl aminopeptidase catalysing hydrolysis of X-prolyl amidomethylcoumarin (AMC) substrates has been purified from Lactococcus subsp. H1. The active enzyme has a molecular mass of approximately 150 kDa, a subunit molecular mass of 82 to 83 kDa and is inhibited by the serine protease inhibitor phenylmethylsulphonyl fluoride. The and values for five different dipeptidyl AMC substrates (Gly-Pro-; Leu-Pro-; Lys-Pro-; Phe-Pro- and Glu-Pro-AMC) are similar except for the value for Glu-Pro-AMC, which is about threefold higher than that for the other substrates. The enzyme also catalyses hydrolysis of X-Ala-AMC substrates but with much lower k and higher values than the corresponding X-Pro-AMC substrates. The β-casein-derived heptapeptides Lys-Ala-Val-Pro-Tyr-Pro-Gln and Tyr-Pro-Phe-Pro-Gly-Pro-Ile were hydrolysed, but bradykinins with N-terminal sequences Arg-Pro-Pro- and Lys-Pro-Pro- were not. Dipeptidyl aminopeptidase specific activity is the same in a plasmid-free strain of subsp. H1 and in the wild-type, indicating that the enzyme is chromosomally encoded.

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/content/journal/micro/10.1099/00221287-137-1-49
1991-01-01
2019-10-14
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http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-137-1-49
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