Enzymatic action of basic arginine amidases in human seminal plasma

Three basic arginine amidases with different affinities to lima bean trypsin inhibitor (LBTI) and aprotinin affinity columns were separated in the middle molecular weight (MMW) preparation obtained from Cellulofine GCL-2000 gel filtration of CM-cellulose adsorbed human seminal plasma and were tentatively called basic human seminal plasma arginine amidase-L (BHSAA-L, with affinity to LBTI), -A (BHSAA-A, with affinity to aprotinin), and -TH (BHSAA-TH, without affinity to either). Some enzymatic properties were measured, including Ki values of LBTI and human seminal plasma proteinase inhibitor (HSP-PI) toward present enzymes. The Ki values of LBTI toward BHSAA-L and -TH were lower than those of HSP-PI and no Ki values for LBTI toward BHSAA-L were observed. The Km values of BHSAA-L and -A to some tripeptidyl-p-nitroanilide substrates seemed relatively lower than that of BHSAA-TH.