Pv. Miranda et al., CHARACTERIZATION OF BETA-N-ACETYLGLUCOSAMINIDASE FROM HUMAN EPIDIDYMIS, International journal of andrology, 18(5), 1995, pp. 263-270
beta-N-acetylglucosaminidase (NAG) activity in human epididymal fluid
was separated into two forms (I and II) after HPLC-hydrophobic interac
tion chromatography. Both forms exhibited maximal activity at a pH of
around 4.5 and had a molecular weight of 125 kD when determined by Sup
erose-HPLC. After incubation at 50 degrees C, form I retained only 30%
of its activity while form II retained 90% activity. When analysed by
non-denaturing electrophoresis, form I displayed higher electrophoret
ic mobility than did form II. These features indicate that the I and I
I isoforms found in the human epididymis are the A and B forms present
in other tissues. NAG activity was measured in the fluid obtained for
m the different epididymal regions of 13 different samples. An average
four-fold increase in activity between the proximal caput and distal
corpus was found. The contribution of each isoform to the total activi
ty was studied. The proximal caput found to be rich in the A isoform (
59%), whereas the B form was predominant in the distal corpus (65%). H
uman spermatozoa contain membrane-associated NAG activity with an isof
orm distribution similar to that found in cauda epididymal fluid (CEP,
80% B). Finally, enzyme activity in CEP was two-fold greater than in
seminal plasma. Taken together these results suggest that NAG may beco
me associated with human spermatozoa during epididymal transit.