Myosin cycles between ATP- and ADP-bound states as it takes steps along the acti
ID: 144125 • Letter: M
Question
Myosin cycles between ATP- and ADP-bound states as it takes steps along the actin microfilament. If you introduced the non-hydrolysable analog of ATP, AMP-PNP (adenylyl-imidodiphosphate) at vast molar excess (i.e. lots more of it than existing ATP and ADP) to an in vitro system of actin-myosin, what would happen? Myosin cycles between ATP- and ADP-bound states as it takes steps along the actin microfilament. If you introduced the non-hydrolysable analog of ATP, AMP-PNP (adenylyl-imidodiphosphate) at vast molar excess (i.e. lots more of it than existing ATP and ADP) to an in vitro system of actin-myosin, what would happen?Explanation / Answer
Myosin and actin act together for muscle movements. The molecular mechanism is as follows–
Cycle starts with myosin tightly bound to actin, in the absence of ATP. When ATP is available, it binds to myosin and thus it is hydrolysed. This results in a conformational change in myosin. This displaces the myosin protein along the actin fibre. After the release of the bound ADP and Pi, myosin come backs to its initial position and binds itself to actin fibre. Now in the presence of large molar concentrations of AMP-PNP in vast molar concentrations would result in the inhibition of this process. And thus muscle contraction and relaxation will not function.
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