1smf

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spinqualitylabelsall models 1smf, resolution 2.1Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STUDIES ON AN ARTIFICIAL TRYPSIN INHIBITOR PEPTIDE DERIVED FROM THE MUNG BEAN INHIBITOR

Overview

The active fragment with Lys at the reactive site of mung bean trypsin, inhibitor (MBILF) is composed of two peptide chains, A1 of 26 residues and, A2 of 9 residues linked via two disulfide bonds. In the present study, a, peptide of 22 residue comprising the sequence of chain A1 from position 3, to 24 was synthesized by the solid-phase method. This synthetic peptide, with six Cys residues contains a reactive site at position Lys11I-Ser12I, (I denotes an inhibitor residue). Air oxidation and HPLC purification, resulted in two antitrypsin active components, SPC1 and SPC2. Neither SPC1, nor SPC2 can stoichiometrically inhibit trypsin. The Ki values of SPC1 and, SPC2 are 1.2 x 10(-7) and 4.0 x 10(-8) M, respectively. The complexes of, SPC1 and SPC2 with bovine beta-trypsin (BTRY) were crystallized by, ammonium sulphate precipitation at pH 6.4 and 6.0, respectively. The two, crystals have the same crystal form with space group P2(1)2(1)2(1) and, cell dimension of a = 63.2(2) A, b = 63.5(6) A, and c = 69.8(4) A. The, crystal structure of one complex, SPC1-BTRY, was determined and refined at, 2.2 A resolution to a final R-value of 19.2%. From the resulting electron, density map, 9 residues of SPC1, from position 9I to 17I, were identified, clearly and three-dimension atomic model of the 9-residue reactive loop, formed by a disulfide bridge, Cys9I-Cys17I, was built. No electron density, corresponding to the other 13 residues was observed in the present, map.(ABSTRACT TRUNCATED AT 250 WORDS)

About this Structure

1SMF is a Protein complex structure of sequences from [1] with CA as ligand. Active as Trypsin, with EC number 3.4.21.4 Full crystallographic information is available from OCA.

Reference

Studies on an artificial trypsin inhibitor peptide derived from the mung bean trypsin inhibitor: chemical synthesis, refolding, and crystallographic analysis of its complex with trypsin., Li Y, Huang Q, Zhang S, Liu S, Chi C, Tang Y, J Biochem (Tokyo). 1994 Jul;116(1):18-25. PMID:7798176

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