1. Introduction of non-natural amino acid residues into the substrate-specific P1 position of trypsin inhibitor SFTI-1 yields potent chymotrypsin and cathepsin G inhibitors.
- Author
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Łegowska A, Debowski D, Lesner A, Wysocka M, and Rolka K
- Subjects
- Amino Acid Sequence, Amino Acids metabolism, Animals, Cattle, Chymotrypsin chemistry, Chymotrypsin metabolism, Humans, Molecular Sequence Data, Peptides chemistry, Peptides pharmacology, Peptides, Cyclic pharmacology, Structure-Activity Relationship, Substrate Specificity, Amino Acids chemistry, Cathepsin G antagonists & inhibitors, Chymotrypsin antagonists & inhibitors, Enzyme Inhibitors chemistry, Peptides, Cyclic chemistry, Trypsin Inhibitors chemistry
- Abstract
A series of trypsin inhibitor SFTI-1compounds 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-NH(2)) and Phe(p-CH(3)) 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.
- Published
- 2009
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