Molecular Human Reproduction, Vol 3, 1061-1066, Copyright © 1997 by Oxford University Press
R Peeker, L Abramsson and SL Marklund
Superoxide radicals may exert both toxic and physiological regulating
actions on spermatozoa. The objective of the present study was to examine
the occurrence and distribution of the three superoxide dismutase (SOD)
isoenzymes in human seminal plasma and spermatozoa. Human seminal plasma
has previously been reported to possess high SOD activity. Here we show
that the normally cytosolic CuZn-SOD remarkably accounts for 75% of the
activity while the secretory extracellular SOD (EC-SOD) accounts for 25%.
Studies of split ejaculates suggest that both these SOD isoenzymes are of
primarily prostatic origin. The Mn-SOD activity was negligible. The total
SOD activity of seminal plasma was 20 times higher than that of human blood
plasma. While native EC-SOD shows high affinity for heparin and heparan
sulphate, 90% of the EC-SOD in seminal plasma lacks the high affinity at
ejaculation. Thus only a minor part of the seminal plasma EC-SOD has the
potential to bind to cell surfaces. Human spermatozoa were found to contain
exceptionally large amounts of CuZn-SOD. There was little Mn-SOD activity
and the amount of EC-SOD was negligible. We conclude that spermatozoa in
semen are exceptionally well protected against superoxide radicals both
internally and externally. This should be of importance for both their
survival and the integrity of DNA, and may also have physiological effects
such as influencing capacitation.
JOURNAL ARTICLE
Superoxide dismutase isoenzymes in human seminal plasma and spermatozoa
Department of Urology and Andrology, Umea University Hospital, Sweden.
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