Modification of the amino group of isoleucine-16 in chymotrypsin with retention of activity
| Autor: | Mario A. Marini, Suraj P. Agarwal, Terence T. Blair, Charles J. Martin |
|---|---|
| Rok vydání: | 1971 |
| Předmět: |
Chemical Phenomena
Ultraviolet Rays Stereochemistry Acylation Potentiometric titration Amidines Biophysics Acetates Biochemistry Anhydrides Amidine Residue (chemistry) chemistry.chemical_compound Chymotrypsin Organic chemistry Trypsin Isoleucine Molecular Biology Enzyme Precursors Binding Sites biology Chemistry Hydrolysis Imidazoles Tryptophan Active site Substrate (chemistry) Esters Cell Biology Hydrogen-Ion Concentration Enzyme Activation Kinetics Cinnamates Spectrophotometry Picolines Chromatography Gel Potentiometry biology.protein Specific activity |
| Zdroj: | Biochemical and Biophysical Research Communications. 43:510-515 |
| ISSN: | 0006-291X |
| DOI: | 10.1016/0006-291x(71)90643-7 |
| Popis: | The N-terminal isoleucine-16 residue of δ-chymotrypsin has been modified to the corresponding amidine by reaction with either ethyl acetimidate or methyl picolinimidate. The modified δ-enzymes show no change in specific activity or in the active site concentration but have one less isoleucine amino group as determined by both end-group analysis and potentiometric titration. Despite the fact that the amidinated amino group has a pK′ about 12, k cat K′ m versus pH profiles (acetyl-L-tryptophan ethyl ester as substrate) are bell-shaped with the upper pK′ 9.3. Thus, the Ile-16 amino group is neither essential for chymotrypsin activity nor responsible for the kinetically seen group with pK′ 9. |
| Databáze: | OpenAIRE |
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