[Polarized ultraviolet fluorescence microscopic study of the structural changes in muscle fiber contractile proteins. V. The possible nature of the conformational rearrangements in heavy meromyosin in fiber relaxation].
The mode and degree of tryptophanyl orientation relative to muscle fiber axes within hydrophobic and hydrophylic sites of myosin macromolecule in the presence of a fluorescence quencher (acrylamide, NO-3) during rigor and relaxation of glycerinated muscle fibers were studied using the polarized ultraviolet fluorescent microscopy. It was shown that myosin tryptophanyls both in LMM and HMM are oriented with their short axes along the longer axis of muscle fiber. Tryptophanyls in LMM have a more pronounced anisotropy of orientation in comparison with the fluorophore orientation anisotropy in hydrophobic sites of HMM. During the muscle fiber relaxation, conformational changes in HMM take place owing to which a section of polypeptide chain with a hydrophilic fluorophore is probably submerged deep into the macromolecule and becomes unapprochable to the quencher.
D000818:Animals; D066298:In Vitro Techniques; D008856:Microscopy, Fluorescence; D008859:Microscopy, Polarization; D008860:Microscopy, Ultraviolet; D008968:Molecular Conformation; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000032:analysis*; D009126:Muscle Relaxation; D009132:Muscles / Q000166:cytology*; D015879:Myosin Subfragments / Q000032:analysis*; D009218:Myosins / Q000032:analysis; D011817:Rabbits
D009124:Muscle Proteins; D015879:Myosin Subfragments; D009218:Myosins
Izuchenie strukturnykh izmeneniĭ sokratitel'nykh belkov myshechnogo volokna s pomoshch'iu poliarizatsionnoĭ ul'trafioletovoĭ fluorestsentnoĭ mikroskopii. V. O vozmozhnom kharaktere konformatsionnykh perestroek tiazhelogo meromiozina pri rasslablenii volokna.