Patterns of intrinsic birefringence were revealed in formalin-fixed, glycerinated myofibrils from rabbit striated muscle, by perfusing them with solvents of refractive index near to that of protein, about 1.570. The patterns differ substantially from those obtained in physiological salt solutions, due to the elimination of edge- and form birefringence. Analysis of myofibrils at various stages of shortening has produced results fully consistent with the sliding filament theory of contraction. On a weight basis, the intrinsic birefringence of thick-filament protein is about 2.4 times that of thin-filament protein. Nonadditivity of thick- and thin-filament birefringence in the overlap regions of A bands may indicate an alteration of macromolecular structure due to interaction between the two types of filaments.
Article| December 01 1971
INTRINSIC BIREFRINGENCE OF GLYCERINATED MYOFIBRILS
Richard H. Colby
From the Department of Cytology, Dartmouth Medical School, Hanover, New Hampshire 03755, and the Group in Biophysics, University of California, Berkeley, California 94720.
Dr. Colby's present address is the Division of Natural Sciences and Mathematics, Stockton State College, Pomona, New Jersey 08240.
Received: May 28 1971
Online Issn: 1540-8140
Print Issn: 0021-9525
Copyright © 1971 by The Rockefeller University Press
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Richard H. Colby; INTRINSIC BIREFRINGENCE OF GLYCERINATED MYOFIBRILS . J Cell Biol 1 December 1971; 51 (3): 763–771. doi: https://doi.org/10.1083/jcb.51.3.763
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