Acid pH crystallization of the basic protein lysin from the spermatozoa of red abalone (Haliotis rufescens).

A new crystal form of dimeric red lysin, a distinctly basic protein (M(r) = 16 070) from the red abalone (Haliotis rufescens), has been obtained using ammonium sulfate as precipitant with a sodium citrate-boric acid-citric acid buffer at pH 4.5. The acid pH crystal form resulted from a study aimed at developing conditions favorable to the sitting-drop vapor-diffusion crystallization of other abalone lysins which do not crystallize at neutral or basic pH conditions. The space group is P222(1) with cell dimensions a = 51.2, b = 47.0, c = 123.8 A and two molecules per asymmetric unit.