Journal
BIOORGANIC & MEDICINAL CHEMISTRY
Volume 17, Issue 9, Pages 3302-3307Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.bmc.2009.03.045
Keywords
Inhibitors, Peptides; Chemical synthesis; Cathepsin G; Chymotrypsin; Phenylalanine derivatives
Funding
- University of Gdansk [BW/8000-5-0125-8]
- Ministry of Science and Higher Education [2889/H03/2008/34]
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A series of trypsin inhibitor SFTI-1 compounds modified in substrate-specific P-1 position was synthesized by the solid-phase method. Lys5 present in the wild inhibitor was replaced by Phe derivatives substituted in para position of the phenyl ring, L-pyridylalanine and N-4-nitrobenzylgycine. Their inhibitory activities with bovine alpha-chymotrypsin and cathepsin G were estimated by determination of association equilibrium constants (K-a). All analogues inhibited bovine alpha-chymotrypsin. The highest inihbitory activity displayed peptides with the fluorine, nitro and methyl substituents. They were 13-15-fold more active than [Phe(5)] SFTI-1 used as a reference. They are the most potent chymotrypsin inhibitors of this size. Substitution of Lys5 by Phe did not change the cathepsin G inhibitory activity. Introduction of Phe( p-F), Phe (p-NH2) and Phe(p-CH3) in this position retained the affinity towards this proteinase, whereas Phe(p-guanidine) gave an inhibitor more than twice as active, which appeared to be stable in human serum. On the other hand, a peptomeric analogue with N-4-nitrobenzylglycine failed to inhibit cathepsin G. Despite the fact the introduced amino acids were non-coded, the peptide bonds formed by them were hydrolyzed by chymotrypsin. We postulate that additional interaction of para-substitutents with the enzyme are responsible for the enhanced inhibitory activity of the analogues. (C) 2009 Elsevier Ltd. All rights reserved.
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