Isolation and Purification of Vitelline‐Coat Lysin from Testis of Turbo cornutus (Mollusca)

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Abstract
A substance causing swelling of the vitelline coat (vitelline‐coat lysin) was extracted from the testis of a sea snail, Turbo cornutus. Its activity was quantified by a volumetric method using a suspension of vitelline coat isolated from T. cornutus eggs. The lysin was purified 50‐fold by hydroxyapatite and Bio‐Gel P‐10 column chromatographies and the final preparation appeared homogenous on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Its molecular weight was estimated to be 18,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and 18,000 by sedimentation equilibrium analysis. These results suggested that the lysin exists as a monomeric molecule. Its isoelectric point was pH 6.4. The lysin contained residues of most common amino acids except cystine and cysteine, with relatively high proportions of lysine, aspartic acid and leucine. The N‐terminal amino acid was identified as serine. The lysin loosened the fibrous structure of the vitelline coat without releasing any soluble product and seemed to act by a stoichiometric, nonenzymatic mechanism.