TY - JOUR
T1 - Fraction of myosin cross-bridges bound to actin in active muscle fibers
T2 - Estimation by fluorescence anisotropy measurements
AU - Burghardt, T. P.
AU - Ajtai, K.
PY - 1985
Y1 - 1985
N2 - Time-resolved and steady-state fluorescence anisotropy measurements from fluorescence-labeled myosin cross-bridges in single glycerinated skeletal muscle fibers in rigor, relaxed, MgADP-induced, and contracting states have been made in order to estimate the fraction of actin-bound cross-bridges in active muscle. When the plane of polarization of the excitation light is perpendicular to the fiber axis and its propagation vector has a component parallel to this axis, actin-bound cross-bridge states, such as rigor and MgADP-induced, have time-zero and steady-state anisotropies that are substantially lower than has the relaxed state. This difference provides a means of determining the fraction of cross-bridges bound to actin in active isometric fibers, by comparing the fluorescence anisotropy from active fibers with the anisotropy from bound and unbound cross-bridges in static states. By assuming that the active cross-bridges are either bound (in the manner of vigor or MgADP-induced states) or relaxed, we estimate that > 80% of the cross-bridges are actin-bound in active isometric fibers.
AB - Time-resolved and steady-state fluorescence anisotropy measurements from fluorescence-labeled myosin cross-bridges in single glycerinated skeletal muscle fibers in rigor, relaxed, MgADP-induced, and contracting states have been made in order to estimate the fraction of actin-bound cross-bridges in active muscle. When the plane of polarization of the excitation light is perpendicular to the fiber axis and its propagation vector has a component parallel to this axis, actin-bound cross-bridge states, such as rigor and MgADP-induced, have time-zero and steady-state anisotropies that are substantially lower than has the relaxed state. This difference provides a means of determining the fraction of cross-bridges bound to actin in active isometric fibers, by comparing the fluorescence anisotropy from active fibers with the anisotropy from bound and unbound cross-bridges in static states. By assuming that the active cross-bridges are either bound (in the manner of vigor or MgADP-induced states) or relaxed, we estimate that > 80% of the cross-bridges are actin-bound in active isometric fibers.
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U2 - 10.1073/pnas.82.24.8478
DO - 10.1073/pnas.82.24.8478
M3 - Article
C2 - 3866235
AN - SCOPUS:0022295424
SN - 0027-8424
VL - 82
SP - 8478
EP - 8482
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 24
ER -