Interaction between Duodenase, a Proteinase with Dual Specificity, and Soybean Inhibitors of Bowman--Birk and Kunitz Type

I. P. Gladysheva^1*, T. S. Zamolodchikova², E. A. Sokolova², and N. I. Larionova¹

¹School of Chemistry, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-5417; E-mail: lar_lab@enzyme.chem.msu.ru

²Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, Moscow, 117871 Russia; fax: (095) 310-7007

^* To whom correspondence should be addressed.

Received April 29, 1999; Revision received June 24, 1999

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The interaction between duodenase, which belongs to a group of Janus-faced proteinases, and classical Bowman--Birk (BBI) and Kunitz (STI) type inhibitors from soybean was investigated. Duodenase was shown to interact only with the antichymotrypsin site (Leu-Ser) of BBI, whereas the antitrypsin site (Lys-Ser) of the inhibitor appeared to be vacant and capable of interaction with trypsin. The inhibition constants of duodenase by BBI, the BBI--trypsin complex, and STI were 4, 400, and 40 nM, respectively.

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KEY WORDS: duodenase, Bowman--Birk inhibitor, Kunitz inhibitor, specificity, inhibition constant

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