Document Detail


Polarized fluorescence depletion reports orientation distribution and rotational dynamics of muscle cross-bridges.
MedLine Citation:
PMID:  12124286     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The method of polarized fluorescence depletion (PFD) has been applied to enhance the resolution of orientational distributions and dynamics obtained from fluorescence polarization (FP) experiments on ordered systems, particularly in muscle fibers. Previous FP data from single fluorescent probes were limited to the 2(nd)- and 4(th)-rank order parameters, <P(2)(cos beta)> and <P(4)(cos beta)>, of the probe angular distribution (beta) relative to the fiber axis and <P(2d)>, a coefficient describing the extent of rapid probe motions. We applied intense 12-micros polarized photoselection pulses to transiently populate the triplet state of rhodamine probes and measured the polarization of the ground-state depletion using a weak interrogation beam. PFD provides dynamic information describing the extent of motions on the time scale between the fluorescence lifetime (e.g., 4 ns) and the duration of the photoselection pulse and it potentially supplies information about the probe angular distribution corresponding to order parameters above rank 4. Gizzard myosin regulatory light chain (RLC) was labeled with the 6-isomer of iodoacetamidotetramethylrhodamine and exchanged into rabbit psoas muscle fibers. In active contraction, dynamic motions of the RLC on the PFD time scale were intermediate between those observed in relaxation and rigor. The results indicate that previously observed disorder of the light chain region in contraction can be ascribed principally to dynamic motions on the microsecond time scale.
Authors:
Marcus G Bell; Robert E Dale; Uulke A van der Heide; Yale E Goldman
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biophysical journal     Volume:  83     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  2002 Aug 
Date Detail:
Created Date:  2002-07-18     Completed Date:  2003-02-21     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1050-73     Citation Subset:  IM    
Affiliation:
Pennsylvania Muscle Institute, The School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6083, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biophysical Phenomena
Biophysics
Chickens
Entropy
Escherichia coli / metabolism
Gizzard
Models, Statistical
Muscle Contraction
Muscles / metabolism
Myosin Light Chains / chemistry*
Myosins / metabolism
Protein Binding
Rabbits
Spectrometry, Fluorescence / methods*
Time Factors
Grant Support
ID/Acronym/Agency:
GM08275/GM/NIGMS NIH HHS; R01-AR26846/AR/NIAMS NIH HHS
Chemical
Reg. No./Substance:
0/Myosin Light Chains; EC 3.6.4.1/Myosins
Comments/Corrections

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