The effect of some proteinase inhibitors on liquefaction of human semen

Abstract

This study examined the effect of some proteinase inhibitors on liquefaction of human semen. It revealed that a strong plasmin inhibitor, 6-amidino-2-naphthyl-6-guanidinobenzoate dihydrochloride (Fusan) showed a significant inhibition of liquefaction, while t-amino caproic acid (t-ACA) showed a weak retardation effect. In terms of sperm quality after liquefaction, Fusan (10 mM), ethyl diamine tetra-acetic acid (EDTA) and Urinastatin completely inhibited sperm motility. Fusan (1 mM) and Lima bean trypsin inhibitor (LBTI) decreased sperm motility significantly, while leupeptin and t-ACA had little effect. Leupeptin, LBTI, t-ACA and Fusan (1 mM) did not affect sperm speed. 50% inhibition of sperm motility was calculated to be approximately 1.7 mM of Fusan concentration. In addition, two inhibitors, Chymostatin and Phosphoramidon were also tested with each experiment and had no effect on liquefaction or on sperm motility and speed. These results strongly suggest that plasmin may play an important role in the liquefaction process of human semen.

Purification and Characterization of Human Kallikrein 11, a Candidate Prostate and Ovarian Cancer Biomarker, from Seminal Plasma

“…It has been suggested that it is involved in the activation of transforming growth factor-h1 in seminal plasma (36) and that it is associated with sperm motility (37). A potent plasmin inhibitor can inhibit semen liquefaction (38). Furthermore, the plasmin-plasminogen activator system has been reported to crosstalk with hK2 and hK3 (39,40).…”

Amidolytic Activities and Prostate-Specific Antigen in Human Seminal Plasma

“…We found significant correlations among the concentrations of individual amidolytic activities measured in this investigation ( Figure 1, Table 1), suggesting that the physiological roles of these amidolytic enzymes measured are strongly correlated. The presence of proteolytic enzymes in the human seminal plasma has been confirmed, which show synthetic peptidyl arginine amido or ester hydrolyzing activity and Val-CHA-Arg-pNA amidolysis or benzoyl-L-arginine ethyl ester (Bz-Arg-Et) esterolysis, such as tissue kallikrein [7], plasmin [18], t-PA [21], thrombin [21], and basic and acidic arginine amidases [12,13,17]. Of these, plasmin, t-PA, and thrombin constitute the proteinase cascade that is involved in the coagulation and liquefaction process of human semen [18,24].…”

“…The presence of proteolytic enzymes in the human seminal plasma has been confirmed, which show synthetic peptidyl arginine amido or ester hydrolyzing activity and Val-CHA-Arg-pNA amidolysis or benzoyl-L-arginine ethyl ester (Bz-Arg-Et) esterolysis, such as tissue kallikrein [7], plasmin [18], t-PA [21], thrombin [21], and basic and acidic arginine amidases [12,13,17]. Of these, plasmin, t-PA, and thrombin constitute the proteinase cascade that is involved in the coagulation and liquefaction process of human semen [18,24]. On the other hand, the present investigation has revealed that the concentrations of all amidolytic activities tested have negative correlations with semen volume, whereas the protein concentration in the semen remains Figure 2.…”

“…Many hydrolytic enzymes, including limited hydrolyzing proteinases and peptidases, are detected in the seminal plasma and appear to play certain roles in various enzymatic functions in the fertilization process, including acrosomal reaction [20,23], dissolution of the zona pellucida [8], and a liquefaction mechanism of ejaculated semen [18,21]. Certain trypsin-like enzymes with amidolytic activity against synthetic arginine and lysine derivatives are found in the semen (seminal plasma), including tissue kallikrein (EC 3.4.21.35) [7,17], tissue plasminogen activator (t-PA, EC 3.4.21.68) [2,15,21,24], and plasminogen/plasmin (EC 3.4.21.7) [14,18,24]; and basic arginine amidases from human and dog were reported by our group [12,13,17] and Frenette et al [5,6]. Seminin [22], which shows chymotrypsin (EC 3.4.21.1) -like amidolytic enzyme activity, appears to control the liquefaction of human semen, but the details are not known.…”

Proteases and Proteases Inhibitors of Semen - A Review

“…A 52 kDa protein expressed on the seminal vesicle, seminogelin is known to play an important role in spontaneous coagulation and liquefaction of human semen (Matsuda et al, 1994). PSA causes liquefaction of the semen by cleavage of seminogelin and results in progressive release of motile spermatozoa and is capacitated (Robert et al, 1997).…”