Summary. The acrosomal matrix of hamster spermatozoa was enriched and characterized. Acrosomal matrices were released from spermatozoa with shaking in a pH 5·2 buffer containing Triton X-100 and protease inhibitors, and enriched on a glass-bead column. Phase-contrast microscopy indicated that 70–80% of the acrosomal matrices were released from the spermatozoa and only minor contamination from sperm heads was detected. Transmission electron microscopy confirmed the low level of contamination in the preparation and revealed a bilaminar structure similar but not identical to that of guinea-pig acrosomal matrix. One- and two-dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed the acrosomal matrix to be a complex structure enriched for several polypeptides. Proteinase activity was demonstrated by gelatin–SDS-PAGE. The major activity corresponded to bands of relative molecular masses (M r) of 56 000, 51 000 and 48 000 with two minor bands of M r 30 000 and 28 000. The lectin Pisum sativum agglutinin (PSA) bound to the anterior head of spermatozoa and isolated acrosomal matrix as judged by fluorescence microscopy using FITC–PSA. Western blots of spermatozoa and acrosomal matrices followed by overlay with biotinylated PSA indicated that there are at least two PSA-binding glycoproteins of M r 60 000 and 72 000.
Keywords: acrosome; acrosomal matrix; hamster spermatozoa; acrosin; proacrosin