Abstract
Two diastereomeric groups of compounds, peptides of the general formula Ala4-Lys-Phe and Ala5-Lys-Phe and p-nitrobenzyl esters of tri-, tetra-, and pentaalanine residues, were synthesized and subjected to enzymic hydrolysis by porcine elastase. The bond cleaved in the peptide substrates is between Ala and Lys, and in the p-nitrobenzyl esters the ester bond is cleaved. By comparing ring Km and kcat values of the appropriate pairs of substrates, we can show that the active site of elastase extends over about 25 Å (seven sub-sites). Elastase does not catalyze the hydrolysis of esters of the d form, and stereospecificity decreases as the distance from the cleaved bond increases. When a D residue is placed at the N terminal of the substrate, no effect on the mode of binding (Km) or on the catalytic power (kcat) is observed.
Original language | English |
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Pages (from-to) | 2573-2577 |
Number of pages | 5 |
Journal | Biochemistry |
Volume | 12 |
Issue number | 14 |
DOIs | |
State | Published - 1 Jul 1973 |
Externally published | Yes |