[Polymerization of myorod, a surface protein of thick filaments of molluscan smooth muscle].

The study is concerned with the polymerization of myorod, a protein from thick filaments of molluscan smooth muscles, which is an alternative product of the gene of myosin heavy chains. The dependences of the properties and polymer structure of myorod on the conditions of its formation were investigated. It was shown that myorod loses the ability to form viscous polymers after proteolytic removal of the unique sequence. It was supposed that the specificity of polymerization of myorod are determined by its unique N-terminal sequence.

[N-ethylmaleimide inhibits polymerization of myorod, a contractile protein of thick filaments of molluscan smooth muscles]. / N-étilmaleimid ingibiruet polimerizatsiiu mioroda--sokratitel'nogo belka tolstykh nitei gladkikh myshts molliuskov.

The effect of N-ethylmaleimide on the polymerization of myorod, a protein of molluscan smooth muscles, which is colocalized with myosin on the surface of paramyosin core of thick filaments and is a product of the alternative splicing of the gene of heavy myosin chains, was studied. It was shown that myorod modified by N-ethylmaleimide completely loses the polymerization ability but acquires the ability to aggregate in the presence of Mg2+. At the same time, treatment of molluscan myosin with N-ethylmaleimide did not affect its polymerization. It was supposed that the effect of N-ethylmaleimide on myorod polymerization is related to the modification of the myorod SH domain containing Cys722.

[A mechanism for dual-stage kinetics of actomyosin superprecipitation]. / Mekhanizm dvustadiinoi kinetiki superpretsipitatsii aktomiozina.

It has been shown that a step-like superprecipitation of actomyosin is determined by parallel processes of two types of superprecipitation: "immediate", which is characterized by a rapid one-step increase in turbidity, and "spontaneous", when slow increase growth of turbidity follows a clear phase. It is suggested that this phenomenon is based on heterogeneous nature of particle sizes in the original suspension, which, under certain conditions, leads to "constriction" of larger particles and "clearing" of smaller ones.

[Change in the size of particles in actomyosin suspensions during superprecipitation]. / Izmenenie razmera chastits v suspenziiakh aktomiozina v protsesse superpretsipitatsii.

Changes in the properties of natural actomyosin suspensions, such as turbidity, light scattering, volume concentration, particle size and particle size distribution during superprecipitation (SPP) of actomyosin in media of different compositions have been investigated. Two sets of changes indicating the existence of two SPP types--the "immediate" SPP characterized by a rapid one-step rise in turbidity and the "spontaneous" SPP, when the slow increase in turbidity follows the clear phase, have been revealed. In both cases the mechanism of the increase in the suspension turbidity is assumed to be similar and is conditioned by an increase in the refraction index (density) of the particles; however, the ways of formation of dense particles are different. During the "immediate" SPP, the particle density increases due to particle striction, whereas during the "spontaneous" SPP dense particles are formed as a result of ordered lateral association of myosin and actin filaments.

[Need to measure the viscosity of solutions of globular proteins when studying their rotational mobility by the spin probe method]. / O neobkhodimosti izmereniia viazkosti rastvorov globuliarnykh belkov pri issledovanii ikh vrashchatel'noi podvizhnosti metodom spinovogo zonda

It is shown that for correct determination of correlation time of protein rotation, at least for high concentration, it is necessary to measure the viscosities of investigated solvents, whereas for definition by method of extrapolation values Azz the viscosity of water solution of sucrose may be taken as the viscosity of investigated solutions.