Domain structure of myosin subfragment‐1

Abstract

The structure of the myosin subfragment-l (SI) from rabbit skeletal muscle was studied using differential scanning microcalorimetry. Three independently melting regions (domains) were revealed in Sl. Selective denaturation of the middle 50 kDa segment of the SI heavy chain resulted in the disappearance of the heat sorption peak corresponding to the melting of the first, the most thermolabile domain without any effect on the thermally induced blue shift of the intrinsic tryptophan fluorescence spectrum which occurs within the temperature region of melting of the second domain. It is concluded that the most thermolabile domain seems to correspond to the N-terminal part of the 50 kDa segment devoid of tryptophan residues.

Interaction of myosin subfragment 1 with F‐actin studied by differential scanning calorimetry

“…Calorimetric measurements were carried out on a differential adiabatic scapning microcalorimeter DASM-4 (Institute for insmmlentation in biology, Pushchino, Russia) as described earlier [5][6][7][8]. All measurements were carried out in 15 mM HEPES/KOH, pH 7.3, containing 0.2 mM ADP and 2 mM MgC12, at a constant heating rate l°C/min.…”

“…Previously, this method was successfully used to study actin polymerization [3] and interaction of F-actin with membrane lipids [4] and with phosphate analogues [5]. The thermal unfolding and domain structure of S1 and their changes induced by nucleotide binding have also been studied by the DSC method [6][7][8].…”

Folding of the Striated Muscle Myosin Motor Domain

“…The core motif that is the heart of the myosin motor domain is discontinuous and includes segments of primary structure from the entire length of the 780-residue catalytic domain. Thus, it is not surprising that the myosin motor domain has not been refolded once denatured in vitro (4) or successfully expressed in bacterial expression systems as, for example, the much more compact and structurally related kinesin motor domain (5).…”

Thermal denaturation of the alkali light chain‐20 kDa fragment complex obtained from myosin subfragment 1

“…The thermal stability of this domain was different in the S1 isol'orrns containing alkali light chains A1 or A2 [9]. In the present work we have investigated the thermal denaturation of the isolated compl0x of the 20 kDa fragment of the S1 heavy chain with alkali light chain.…”

“…Recently we have studied the thermal denaturation of $1 by means of differential scanning microcalorimetry using the successive annealing method [8,9] [8]. The thermal stability of this domain was different in the S1 isol'orrns containing alkali light chains A1 or A2 [9].…”