Isolation, Purification, and Properties of Cysteine Proteinase from Bombyx mori L. Eggs

D. V. Yarygin^*, S. M. Klunova, and Yu. B. Filippovich

Department of Organic and Biological Chemistry, Moscow State Pedagogical University, ul. Kibalchicha 6, Moscow, 129278 Russia

^* To whom correspondence should be addressed.

Received November 9, 2001; Revision received January 25, 2002

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Silkworm moth (bombyx) egg cysteine proteinase with maximal activity at pH 3.0 was purified by chromatography and isoelectrofocusing. On SDS-electrophoresis in polyacrylamide gel the purified enzyme showed a single band of molecular mass 50 kD. Isoelectrofocusing revealed that the bombyx egg cysteine proteinase exists in two forms with pI values of 5.95 and 6.43, respectively. The enzyme activity was sensitive to inhibition by iodoacetamide and p-chloromercuribenzoate but resistant to EDTA, pepstatin, and phenylmethylsulfonyl fluoride. The cysteine proteinase hydrolyzes storage proteins of bombyx eggs but it was inactive with respect to N-benzoyl-D,L-arginine-p-nitroanilide (BAPNA). It is a cathepsin L-like enzyme.

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KEY WORDS: cysteine proteinase, eggs, silkworm moth, bombyx, Bombyx mori L.

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