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Characterization of human semen alpha-L-fucosidases.
J A Alhadeff1, S Khunsook, K Choowongkomon
1Department of Chemistry, 111 Research Drive, Lehigh University, Bethlehem, PA 18015, USA.
Molecular Human Reproduction
|August 25, 1999
Summary
Human sperm possess a distinct alpha-L-fucosidase enzyme on their plasma membrane, differing from the enzyme found in seminal fluid. Further research is needed to understand the specific function of this sperm-associated alpha-L-fucosidase.
Area of Science:
- Biochemistry
- Reproductive Biology
- Enzymology
Background:
- Human semen exhibits significant alpha-L-fucosidase activity, predominantly in seminal fluid.
- Previous studies suggested a minor presence of this enzyme on sperm, particularly in the posterior head region.
Purpose of the Study:
- To characterize and differentiate alpha-L-fucosidase present in human seminal fluid from that associated with sperm.
- To investigate the biochemical properties and localization of sperm alpha-L-fucosidase.
Main Methods:
- Immunocytochemistry for enzyme localization on sperm.
- Subcellular fractionation to isolate membrane-enriched fractions.
- Biochemical assays to determine pH optima and isoelectric points (pI).
- Western blotting to assess molecular mass (M(r)).
Main Results:
- Sperm alpha-L-fucosidase is primarily located on the plasma membrane, distinct from seminal fluid enzyme.
- Sperm fucosidase shows a major pH optimum between 3.4 and 4.0, unlike seminal fluid enzyme (pH 4.8-7.0).
- Distinct isoforms and molecular masses (51 kDa for sperm vs. 56 kDa for seminal fluid) were identified.
Conclusions:
- A low-abundance, distinct alpha-L-fucosidase is associated with the human sperm plasma membrane.
- This sperm-specific enzyme differs biochemically from seminal fluid alpha-L-fucosidase.
- The precise function of sperm alpha-L-fucosidase remains to be elucidated.