Soybean trypsin inhibitor structure

Solanum (potato) Kunitz PEPs inhibit the aspartic protease cathepsin D as well as trypsin [125-134] and potato cysteine protease inhibitor (PCPI) inhibits a variety of cysteine proteases [185-188]. The crystal structures of soybean trypsin inhibitor (STI) [362, 368] and of Erythrina trypsin inhibitor (ETI) [350] have been determined. The structure of this type of plant Kunitz serine PIP involves a [3-barrel formed by 6 loop-linked antiparallel [3-strands with a lid formed by 6 further loop-linked antiparallel [3-strands. The scissile bond is located within a loop that extends out from the surface of the [3-barrel [350, 362, 368]. 

Sweet RM, Wright HT, Janin J, Chothia CH, Blow DM. Crystal structure of the complex of porcine trypsin with soybean trypsin inhibitor (Kunitz) at 2.6-A resolution. Biochemistry 1974 13 4212-4228. 

Primary structures of the Kunitz soybean trypsin inhibitor (A) and the Bowman-Birk soybean trypsin inhibitor (B). The solid black circles on the primary structure of the Bowman-Birk soybean trypsin inhibitor represent LYS-SER arid LEU-SER and are the binding sites far trypsin and chymotrypsin, respectively. Reproduced with permission from (A) Ref 73, copyright 1973, E. J. of Bioch. and (B) Ref 74, copyright 1973, J. Food Biochem.j... 

The first X-ray crystal structures of tetrahedral intermediates were obtained from the porcine trypsin crystallized with soybean trypsin inhibitor in 1974, and the... 

The effects of ethanol on the conformation of aj-antitrypsin, deoxyribonuclease, pepsinogen, soybean trypsin inhibitor, and unfolded ribonucleases have been studied by c.d. spectroscopy. In the presence of 50—75 volume % ethanol, the tertiary structure is perturbed and the polypeptide chain is reorganized into new conformations with higher contents of helix and /3-structure than those in the native state. 

K. Hatano, M. Kojima, M. Tanokura, and K. Takahashi. Solution structure of bromelain inhibitor VI from pineapple stem structural similarity with Bowman-Birk trypsin/chymotrypsin inhibitor from soybean. Biochemistry 35 5379 (1996). 

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