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Preparation and characterization of fluorescent N-(3-pyrene)maleimide adducts of myosin
Abstract:
N-(3-pyrene)maleimide adducts of myosin (PM-myosin) are fluorescent and possess actin-activated Mg2+ ATPase activity. Addition of ATP to PM-myosin produces a reversible decrease of 10% in fluorescence intensity of the pyrene fluorophore in the presence of actin. Analogues of ATP which are poor substrates for myosin ATPase or which merely dissociate actomyosin produce less decrease in fluorescence of PM-myosin than does ATP. Since fluorescence of acto-PM-myosin is sensitive to environmental changes associated with ATP hydrolysis, and/or with fluorophore-actin interactions. PM-myosin may be a useful analysis of molecular aspects of muscle contraction.
Insights
Fluorescent N-(3-pyrene)maleimide adducts of myosin (PM-myosin) show a decrease in fluorescence with ATP addition. This fluorescence change, linked to muscle contraction, makes PM-myosin a potential tool for molecular analysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Muscle Physiology
Background:
- Myosin is a key protein in muscle contraction.
- Fluorescent probes can report on protein conformational changes.
Purpose of the Study:
- To investigate the use of N-(3-pyrene)maleimide adducts of myosin (PM-myosin) as a fluorescent probe.
- To analyze the molecular mechanisms of muscle contraction using PM-myosin.
Main Methods:
- Chemical modification of myosin with N-(3-pyrene)maleimide.
- Measurement of actin-activated Mg2+ ATPase activity.
- Monitoring fluorescence intensity changes upon ATP addition in the presence of actin.
Main Results:
- PM-myosin exhibits fluorescence sensitive to ATP binding and hydrolysis.
- A 10% reversible decrease in fluorescence intensity was observed with ATP addition to acto-PM-myosin.
- ATP analogues with poor substrate properties or actomyosin dissociation capabilities induced smaller fluorescence changes.
Conclusions:
- The fluorescence of PM-myosin is sensitive to the microenvironment changes during ATP hydrolysis and fluorophore-actin interactions.
- PM-myosin serves as a valuable tool for studying the molecular dynamics of muscle contraction.