β Scribed by Waffenschmidt, Sabine ;Knittler, Michael ;Jaenicke, Lothar
No coin nor oath required. For personal study only.
A cell-wall degrading enzyme has been isolated from mature sperm packets of the green flagellate Volvox carteri (Poona strain). This sperm lysin (S-lysin) is a Ca2+-dependent protease of 34 kDa with an essential serine group in its active centre. Neither SH group-blocking reagents nor transition metal chelators inhibit its action. S-lysin degrades the hydroxyproline-rich glycoprotein structures of the cell walls of sheath cells and gonidia (eggs) of vegetative and sexual spheroids in a characteristic manner. In asexual spheroids the somatic envelope is totally disintegrated, whereas in sexual spheroids pores are formed by local lysis at sites of adjacent eggs. Although S-lysin is very similar to the G-lysin of the closely related Chlamydomonads, it is species specific and does not attack the mother or daughter cell walls of Chlamydomonas reinhardtii. S-lysin resembles the acrosin of animal sperm cells in some aspects of its action.
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