The energy utilized in protein breakdown by the ATP-dependent protease (La) from Escherichia coli.

摘要: A crucial enzyme in the pathway for protein degradation Escherichia coli is protease La, an ATP-hydrolyzing encoded by lon gene. This degrades various proteins to small polypeptides containing 10-20 amino acid residues. To learn more about its energy requirement, we determined number of ATP molecules hydrolyzed purified each peptide bond cleaved. The 2 new group generated with casein, bovine serum albumin, glucagon, or guanidinated casein as substrates, even though these differ up 20-fold size and 3-4 fold rates hydrolysis bonds. Similar values stoichiometry (from 1.9 2.4) were obtained using fluorescamine 2,4,6-trinitrobenzene sulfonic estimate appearance groups. These appeared lower at 1 mM than 10 Mg2+. coupling between very tight. However, when was assayed under suboptimal conditions (e.g. pH ADP present), many 3.5 12) consumed per Our data would indicate that early steps consume almost much (2 ATPs cleavage) does formation bonds during synthesis.