What question did this study set out to answer?

To determine whether sulfhydryl groups are directly required for the catalytic mechanism of ATP hydrolysis in myosin.

April 1, 1978Journal of Biological ChemistryOpen Access

The nonessential nature of sulfhydryl groups for ATPase activity in myosin. A cyanylation study.

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Population

Myosin preparations

Comparison

Cyanylation with 6-thiol'4Clcyanato-9-/3-o-ribofu… vs Native enzyme

Design

Preclinical

Authors

HWHannah J. WiednerUniversity of North Carolina at Chapel Hill RWRonald WetzelUniversity of Pittsburgh FEF. EcksteinTokyo Institute of Technology

Discussion

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Implication

Refines myosin ATPase models; leaves open translation to cardiac contractility or disease.

Key Points

To determine whether sulfhydryl groups are directly required for the catalytic mechanism of ATP hydrolysis in myosin.
Cyanylated myosin sulfhydryl groups using 6-thiol-[14C]cyanato-9-β-D-ribofuranosylpurine across varying degrees of modification.
Assayed Mg2+-, Ca2+-, and K+(EDTA)-dependent ATPase activities and tested susceptibility to N-ethylmaleimide inactivation.
Quantified residual free sulfhydryl groups using Ellman's reagent before and after treatment with dithioerythritol.
Initial incorporation of 4 mol cyanide increased Mg2+-dependent ATPase activity approximately eightfold and slightly increased Ca2+ activity, while K+(EDTA) activity fell to approximately 5% of baseline.
Maximal cyanylation reduced free sulfhydryl groups from 39.2 to 0.6 per molecule (with 26 forming disulfide bridges), while maintaining enzymatic activity and sharply elevating Ca2+- and Mg2+-ATPase activity.

Structured PICO

Population

Myosin preparations

Intervention

Cyanylation with 6-thiol'4Clcyanato-9-/3-o-ribofuranosylpurine

Comparator

Native enzyme

Outcome

ATPase activity (Mg2+, Ca2+, K+(EDTA))surrogate

This basic science study demonstrates that sulfhydryl groups in myosin are not essential for ATP hydrolysis but rather affect the conformation of the active site.

Cite This Study

Wiedner et al. (1978) studied this question.

synapsesocial.com/papers/6a89cb4041f4089922bd773a https://doi.org/10.1016/s0021-9258(17)40888-x

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The nonessential nature of sulfhydryl groups for ATPase activity in myosin. A cyanylation study.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

The nonessential nature of sulfhydryl groups for ATPase activity in myosin. A cyanylation study.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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