A conserved cis peptide bond is necessary for the activity of Bowman-Birk inhibitor protein.

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作者：

ABE Brauer，GJ Domingo，RM Cooke，SJ Matthews，RJ Leatherbarrow

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摘要：

The Bowman-Birk inhibitor (BBI) family of protease inhibitors has an inhibitory region comprising a disulfide-linked nine-residue loop that adopts the characteristic canonical motif found in many serine protease inhibitors. A unique feature of the BBI loop is the presence of a cis peptide bond at the edge of the inhibitory loop. BBI-related protein fragments that encapsulate this loop retain the structure and inhibitory activity of the parent protein. The most common BBI loop sequence has a proline-proline element with a cistrans geometry at P3'P4'. We have examined this element by analysis of the inhibitory activity and structure for a series of synthetic fragments where each of these proline residues has been systematically replaced with alanine. The results show that only when a proline is present at P3' are potent inhibition and a cis peptide bond at that position in the solution structure observed, suggesting that this conformation is required for biological activity. Though a P4' proline is not es...

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关键词：

Proline Trypsin Trypsin Inhibitor, Bowman-Birk Soybean Magnetic Resonance Spectroscopy Protein Conformation Substrate Specificity Kinetics Amino Acid Sequence Alanine Isomerism