[Effect of continuous and impulsive ultrasound on actomyosin superprecipitation reaction from rabbit skeletal muscles].

A comparative study of the effect of continuous and impulsive (2 ms) ultrasound regimes on actomyosin superprecipitation reaction of the rabbit skeletal muscles was carried out. From the obtained kinetic curves the value of superprecipitation (D(m) - D(00)), time t1/2, which required to achieve a half its value was determined, and the normalized maximal rate of this reaction V(n) was calculated as well. It is shown that continuous ultrasound with intensities 0.

[Interaction of annexin VI with actin].

Actin polymerization was investigated using fluorescence probe N-(1-pyrenyl)iodoacetamide, which was bound covalently to reactive sulfhydryl group, Cys-373. Labeled actin in the bulk was 0.5 to 1% of total actin concentration.

[Conformational modifications of smooth muscle light chain kinase].

Our recent investigations have shown that smooth muscle myosin light chain kinase (MLCK) exists in solution as a mixture of oligomeric, dimeric and monomeric species; besides during preincubation (maintaining of the activated enzyme without substrate) with substoichiometric amounts of calmodulin (CaM) it undergoes definite changes leading to several fold lowering of its activity. Fluorescent data obtained in this work suggest that such kinase inhibition must not be connected with quantitative redistribution of different kinase species but rather it is the result of conformational modifications of this enzyme activated molecules leading to the reduction of their affinity to CaM. Such conformational rearrangements took place also at equimolar kinase to CaM ratio (or CaM excess) but in this case they were characterized by lower depth and insignificant MLCK activity fall.

[Effect of regulatory light chains of myosin on aggregation of its subfragment-1].

Chymotryptic (Ch-Cl) and Mg(2+)-papain subfragments 1 of (Mg-Cl) skeletal myosin has been studied. Mg-Cl is known to differ from Ch-Cl by the presence of the regulatory light chain (RLC) and elongated heavy chain including C-end hinge segment. Experimental data prove the decisive part of coordination bondings with bivalent cations in stabilization of RLV on myosin head hinge segment.

[Structural characteristics and aggregation of myosin heads in skeletal muscles].

Native conformational modifications of rabbit skeletal muscle myosin and its subfragment-1 (S-1) within the temperature range of 0-40 degrees C and irreversible unfolding of these proteins structure at temperatures 40-70 degrees C have been studied by the fluorescence and light scattering methods. The results obtained permit stating that myosin and its active subfragments form associates at the concentrations above 0.3 microM.

[Spectrofluorimetric detection of two states during melting of ribonuclease T1].

The melting temperature of ribonuclease T1 was studied by the fluorescent method. It was shown that in the melting region the tryptophanyl fluorescence spectrum of the protein containing a single tryptophanyl is the sum of two simple spectra typical for tryptophanyl located in the hydrophobic environment and for tryptophanyl completely accessible to aqueous solvent, correspondingly. This implies the evidence of two forms of the protein, i.