2000
DOI: 10.1074/jbc.m002910200
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Tryptophan 512 Is Sensitive to Conformational Changes in the Rigid Relay Loop of Smooth Muscle Myosin during the MgATPase Cycle

Abstract: It has been well established that muscle contraction is driven by structural rearrangements within myosin during its ATPase cycle and interaction with actin. The crystal structures of myosin (Fig. 1) solved in different nucleotide states have provided a framework for examining the structural basis of the ATPase cycle of myosin (1-6). In addition, solution techniques that include monitoring the intrinsic fluorescence of myosin have proven extremely valuable for examining the enzymatic and kinetic properties of … Show more

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Cited by 58 publications
(81 citation statements)
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“…The actinactivated V max was decreased 3-fold (0.74 s Ϫ1 for WT MDE and 0.23 s Ϫ1 for F344W), whereas the catalytic efficiency (V max /K m ) was increased for the mutant over the wild-type MDE construct (Table 1). This is consistent with other single tryptophan smooth muscle myosin mutants, which show similar decreased activity but increased catalytic efficiency (28,38 (Table 2). K D values in the presence of actin increased to ϳ10 M for each of our constructs, consistent with the 5-fold decrease in affinity previously observed (39).…”
Section: Resultssupporting
confidence: 79%
“…The actinactivated V max was decreased 3-fold (0.74 s Ϫ1 for WT MDE and 0.23 s Ϫ1 for F344W), whereas the catalytic efficiency (V max /K m ) was increased for the mutant over the wild-type MDE construct (Table 1). This is consistent with other single tryptophan smooth muscle myosin mutants, which show similar decreased activity but increased catalytic efficiency (28,38 (Table 2). K D values in the presence of actin increased to ϳ10 M for each of our constructs, consistent with the 5-fold decrease in affinity previously observed (39).…”
Section: Resultssupporting
confidence: 79%
“…Muscle myosins show a similar change in fluorescence as a result of an environmental change around tryptophan 510 (31,32), and an equivalent tryptophan is present in myo1b. We were unable to measure a change in tryptophan fluorescence directly in the presence of actin because of the low signal to noise at 37 °C and the presence of a high fluorescence background from the actin.…”
Section: Atp Hydrolysismentioning
confidence: 95%
“…Tryptophan fluorescence has proved to be a powerful experimental tool when used to characterize the different aspects of myosin interaction with nucleotides [10][11][12][13]. Rapid kinetic experiments using tryptophan fluorescence indicated that the delicately poised equilibrium between the closed and open conformations was influenced by temperature changes in a nucleotide dependent manner [14][15][16].…”
mentioning
confidence: 99%
“…The helix consisting of residues 648-666 is in the fulcrum of this rotation. In conjunction with this transition, the converter domain rotates by 60°, which induces the movement of the C-terminal end of S1 by 12 nm [9].Tryptophan fluorescence has proved to be a powerful experimental tool when used to characterize the different aspects of myosin interaction with nucleotides [10][11][12][13]. Rapid kinetic experiments using tryptophan fluorescence indicated Correspondence to B. Somogyi,…”
mentioning
confidence: 99%
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