Amidolytic activities and prostate-specific antigen in human seminal plasma

The amounts of protein measured by absorbance at 280 nm, succinyl-L-alanyl-L-alanyl-L-prolyl-L-leucine-p-nitroanilide (Suc-Ala-Ala-Pro-Leu-pNA), D-valyl-cyclohexyl-alanyl-L-arginine-p-nitroanilide (Val-CHA-Arg-pNA), and glutamyl-L-phenylalanine-p-nitroanilide (Glu-Phe-pNA) amidolytic activities, and prostate-specific antigen (PSA) were measured in human seminal plasma (HSP) samples separated from the semen of 46 cases, including 13 cases of azoospermia and 33 cases of normozoospermia showing either good or poor quality of liquefaction. There was a highly significant correlation between the concentrations of all amidolytic enzyme activities studied and the concentration of PSA in HSP samples (p<.01). The HSP sample volume showed a relatively good negative coefficient of correlation to all items measured (p<.01) with the exception of protein concentration. The Suc-Ala-Ala-Pro-Leu-pNA, Val-CHA-Arg-pNA, and Glu-Phe-pNA amidolytic activities in azoospermia HSP samples were 2.33. 1.68, and 1.43 times higher, respectively, than those of normozoospermia samples showing good quality liquefaction. After the addition of morphologically purified human sperm to HSP sample of azoospermia cases, the Suc-Ala-Ala-Pro-Leu-pNA amidolytic activity in the HSP sample of azoospermia was not decreased for up to 18 h incubation, while the number of motile human sperm gradually declined, and no motile human sperm were detected after 18 h of incubation. The high Suc-Ala-AlaPro-Leu-pNA amidolytic activity in HSP samples of azoospermia cases did not result from a lack of motility.