What question did this study set out to answer?

To determine the reaction mechanism governing phosphate incorporation and intermediate decomposition in the Ca++-dependent ATPase of rabbit skeletal muscle sarcoplasmic reticulum.

August 1, 1968The Journal of Biochemistry

Reaction Mechanism of the Ca++-Dependent ATPase of Sarcoplasmic Reticulum from Skeletal Muscle*

View Full Paper

Ask AI

Bookmark

Authors

TYTaibo YamamotoKanto Gakuin University YTYūji TonomuraHokkaido University of Science

Discussion

Member takes

Implication

Biochemical analysis reveals intermediate enzyme-phosphate dynamics in rabbit skeletal muscle, demonstrating a multi-step catalytic mechanism during calcium transport.

Key Points

To determine the reaction mechanism governing phosphate incorporation and intermediate decomposition in the Ca++-dependent ATPase of rabbit skeletal muscle sarcoplasmic reticulum.
Incubated rabbit skeletal muscle sarcoplasmic reticulum with radiolabeled gamma-32P-ATP and Ca++ to monitor phosphate incorporation and overall ATPase activity across pH gradients.
Tracked enzyme-phosphate intermediate decomposition kinetics following the addition of 2 mM EGTA, cold unlabeled ATP chase, or magnesium removal.
Tested the chemical stability of the trichloroacetic acid-isolated phosphoenzyme complex in acidic, alkaline, and 0.5 M hydroxylamine-treated media.
Phosphate incorporation increased with pH to a maximum above pH 8.3, while overall ATPase activity peaked at pH 7.0, indicating a catalytic group with a pK of approximately 7.2 participates in complex decomposition.
Decomposition of the intermediate occurred threefold faster following chase with 2 mM cold ATP than after calcium chelation with 2 mM EGTA, whereas magnesium removal did not alter decomposition rates.
The isolated intermediate showed high stability in acidic media but rapid degradation in alkaline conditions and within 0.5 M hydroxylamine.

Cite This Study

Yamamoto et al. (1968) studied this question.

synapsesocial.com/papers/6a1beef61567d2fc4d5f47cc https://doi.org/10.1093/oxfordjournals.jbchem.a128873

View Full Paper

Ask AI

Bookmark

Implication

Biochemical analysis reveals intermediate enzyme-phosphate dynamics in rabbit skeletal muscle, demonstrating a multi-step catalytic mechanism during calcium transport.

Reaction Mechanism of the Ca++-Dependent ATPase of Sarcoplasmic Reticulum from Skeletal Muscle*

Discussion

Member takes

Implication

Key Points

Cite This Study

Reaction Mechanism of the Ca++-Dependent ATPase of Sarcoplasmic Reticulum from Skeletal Muscle*

Discussion

Member takes

Implication

Key Points

Cite This Study

Also Consider

Also Consider