Transient-state Kinetic Studies Research Articles

Transient state kinetic studies of Ca2+-dependent ATPase and calcium transport by cardiac sarcoplasmic reticulum. Effect of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of phospholamban.

Transient state kinetic studies of Ca2+-dependent ATPase and calcium transport by cardiac sarcoplasmic reticulum. Effect of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of phospholamban.

Transient state kinetic studies of Ca 2+-dependent atpase and Ca translocation by cardiac sarcoplasmic reticulum. Role of the 22,000-dalton protein phospholamban

Transient state kinetic studies of Ca 2+-dependent atpase and Ca translocation by cardiac sarcoplasmic reticulum. Role of the 22,000-dalton protein phospholamban

Transient state kinetic studies of Ca 2+-dependent ATPase of cardiac sarcoplasmic reticulum. Effect of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of phospholamban : M. Yamada, M. Tada, F. Ohmori, T. Kuzuya, M. Inui, and H. Abe. First Dept. of Medicine, Osaka Univ. School of Medicine, Osaka, Japan

Transient state kinetic studies of Ca 2+-dependent ATPase of cardiac sarcoplasmic reticulum. Effect of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of phospholamban : M. Yamada, M. Tada, F. Ohmori, T. Kuzuya, M. Inui, and H. Abe. First Dept. of Medicine, Osaka Univ. School of Medicine, Osaka, Japan

Transient state kinetic studies of phosphorylation by ATP and P i of the calcium-dependent ATPase from sarcoplasmic reticulum

The ATPase of the sarcoplasmic reticulum is phosphorylated by ATP in the presence of Ca 2+. A rapid phosphorylation was observed when the enzyme was preincubated with Ca 2+ prior to the addition of 0.1 or 1 mM ATP. The rate of phosphorylation was decreased when Ca 2+ was omitted from the preincubation medium and added with ATP when the reaction was started. The rate of phosphorylation by ATP was further decreased when P i was included in the preincubation medium without Ca 2+. In this case, the enzyme was phosphorylated by P i during the preincubation. When Ca 2+ and ATP were added, a burst of phosphorylation by ATP was observed in the initial 16 ms. In the subsequent incubation intervals, the phosphorylation by ATP was synchronous with the hydrolysis of the phosphoenzyme formed by P i. The rate of hydrolysis of the phosphoenzyme formed by P i was measured when either the P i concentration was decreased 10 fold, or when Ca 2+, ATP or ATP plus Ca 2+ was added to the medium. Upon the single addition of Ca 2+, the time for half-maximal decay was in the range 500–1000 ms. In all other conditions it was in the range 70–90 ms.

Transient state kinetic studies of proton liberation by myosin and subfragment 1

Myosin and subfragment 1 give a maximum burst size of 0.25 to 0.30 protons per active site at pH 8 with ATP, alpha,beta-methylene-ATP, ADP, and adenylyl imidodiphosphate as substrates. The proton is derived from a change in conformation of the enzyme-substrate complex since it is produced by substrates which are not hydrolyzed. The rate constants for the binding of ATP and the proton release step in 0.1 M, 0.5 M, and 1.0 M KCl have been determined by analysis of the concentration dependence of the apparent rate. (see article)