Inhibitors on an elastase-like enzyme activity catalyzing Suc-Ala-Ala-Pro-Leu-pNA amidolysis in human seminal plasma

The behavior of some proteinase inhibitors toward the Suc-Ala-Ala-Pro-Leu-pNA amidolytic enzyme activity in human seminal plasma (HSP) was tested. [(2S, 3R)-3-Amino-2-hydroxy-5-methyl-hexanoyl]L-valyl-L-valyl-L-aspartic acid (Amastatin) and 3-[1-[(2-(hydroxymethyl)- -pyrolidinyl)-2-methylpropyl]-carbamoyl] octanohydroxamic acid (Actinonin) showed strong inhibitory effects. No inhibition of this present enzyme activity was seen with anti-human serum (whole), anti-human leukocyte Elastase, phenyl-methyl sulfonyl fluoride, Elastatinal, ethyeneglycol bis(beta-aminoethyl ethyl)N,N,N:N'-tetra acetic acid, and [L-3-trans-ethoxycarbonyl-oxirane-2-carbonyl]1-L-leucine(3-methylbutyl)a mido (E-64). No relation was observed between human pancreatic Elastase antigen and the Suc-Ala-Ala-Pro-Leu-pNA amidolytic enzyme enzyme activity in HSP. Two peaks of Suc-Ala-Ala-Leu-Pro-pNA amidolytic enzyme activity were separated by Cellulofine GCL-2000 gel filtration and these activities were completely abolished by addition of Amastatin. Suc-Ala-Ala-Pro-Leu-pNA amidolytic enzyme activity in HSP is not an elastase-like metalloproteinase but is rather an acyl amidase-like leucine Aminopeptidase.