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A. Jauhiainen and T. Vanha-Perttula

Summary. The highest specific activity of β-N-acetylglucosaminidase (β-NAG) was found in the different parts of the epididymis, where the activity seemed to be partly in secretory and partly in non-secretory, tissue-bound form. Epididymal spermatozoa also contained moderate β-NAG activity.

The β-NAG was separated by chromatofocussing and anion exchange chromatography with HPLC into multiple forms with distinct pI values (8·0–4·0). The cauda epididymidis, ampulla and the seminal vesicles formed the major secretory sources of the high β-NAG activity in bull seminal plasma. The major secretory forms of β-NAG in caput and cauda epididymidis showed distinct elution profiles. In the fractionation with gel filtration on Sepharose 6B, the β-NAG activities derived from bull testis and caput epididymidis had smaller molecular weights than did the secretory enzymes in seminal plasma, seminal vesicle secretion and cauda epididymidis. Maximum activity of all β-NAG isoenzymes was observed at pH 5·0. They were almost totally inactivated at 60°C and about 75–80% of the activity was lost at 55°C. All the isoenzymes were strongly inhibited by thiol reagents but not with other metal ions and chelating agents.

Histochemical studies showed a strong granular (lysosomal) reaction for β-NAG in basal cells and basal parts of the principal cells in all but the initial segment of the epididymis. An apical (secretory) reaction was prominent in the distal caput and corpus as well as in distal cauda. After the distal caput the luminal sperm mass became increasingly mixed with a β-NAG-positive material. The epithelial cells of the ampulla and seminal vesicle displayed a moderate apical (secretory) reaction.

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A. Jauhiainen and T. Vanha-Perttula

Summary. A synthetic substrate (p-nitrophenyl-α-D-glucopyranoside) was used to measure the acid and neutral α-glucosidase activity in bull seminal plasma, spermatozoa and in homogenates of bull reproductive organs. Marked differences were observed in the activities of these enzymes in the various tissues studied. Epididymis and particularly its caput region contained the highest specific activity of acid αglucosidase. The activity of neutral α-glucosidase was highest in testis and in different parts of the epididymis. Seminal plasma, spermatozoa and seminal vesicle secretion contained only the acid enzyme activity.

After fractionation with anion exchange chromatography in HPLC (Mono Q) and chromatofocussing, acid α-glucosidase activity of seminal plasma was recovered in two fractions with different pI values. The corresponding activities were found in the secretion of seminal vesicles, which thus form the major secretory source of seminal plasma acid α-glucosidase. In the fractionation with gel filtration on Sepharose 6B, the acid α-glucosidase had a smaller molecular weight than did the neutral enzyme. In anion exchange chromatography and chromatofocussing the testicular and epididymal homogenates each contained two acid and two neutral isoenzymes. In both fractionations the elution pattern of acid α-glucosidase was clearly different from that of the enzymes in seminal plasma.

The pH optimum of acid α-glucosidase ranged from 3·75 to 4·5 and that of the neutral enzyme from 6·5 to 7·0. The neutral activity was more sensitive to many divalent metal ions and differences were also observed in the response of the enzymes to different concentrations of turanose and KCl.