| Popis: |
Mild treatment of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase with chymotrypsin, trypsin, subtilisin, or Pronase results in a substantial loss in enzymatic activity of the apoenzyme and not the holoenzyme. The products from proteolytic digestion differ in chemical and physical properties, suggesting that peptide bond cleavages have been introduced in quite different regions of the protein Particularly in the cases of chymotrypsin and trypsin binding of NAD + drastically reduces the susceptibility of all these bonds to hydrolysis. The degree of protection from inactivation is greatest in the case of all proteolyses when less than two coenzyme molecules are bound to a molecule of the tetrameric enzyme. These results are considered in terms of understanding the mechanism for the homotropic effects observed in coenzyme binding. |
