Properties of desensitized actomyosin are not easily reproduced
V. Matveev and S. Galler 
Institute of Cytology, St. Petersburg (Russia)
University of Salzburg, Institute of Zoology (Austria) 

Experimental results 

This work was undertaken in Dr. S. Galler's laboratory (in August, 2001) and is a continuation of Dr. V. Matveev's work published in the Journal "Physiological Chemistry and Physics and Medical NMR". The purpose of the teamwork was a research of an influence of conditions of washing of natural actomyosin (nAM) from Ca2+-sensitive complex on properties of a desensitized actomyosin (dAM) received as a result of this procedure. Centrifuge of Sorvall RC5C (GSA rotor) was used, which technical characteristics are essentially distinguished from the characteristics of centrifuge used in Matveev's work. In the work which was done in Salzburg two dAM preparation were obtained. Protocols of a washing of nAM were differed by KCl contents in washing solution (0.2 and 0.4 mM) and by amount of centrifugation steps (from 12 up to 15), g values and centrifugation time. Obtained dAM preparations were mixed with the same preparation of nAM in a different proportion. After 12-15 hour incubation at 0-4o C a Ca2+-sensitivity of a two-component suspensions were measured as it is described in Matveev's work (see Figure below). The Figure shows comparison of the curve obtained in Matveev's work (curve 1) with two different dAM preparations, obtained in our last experiments (curves 2 and 3).  It is obvious that the three different dAM preparations differently influence on the Ca2+-sensitivity of the two-component suspensions (the most inhibitory activity of dAM is demonstrated by curve 1). Hence, reproduction of dAM properties, used in Matveev's work is not a simple experimental task.

The data received by us put the following problems: 
(i) It is necessary to develop a protocol of preparation of dAM, which would be reliably reproduced;

(ii) It is necessary to find quantity indicators of dAM properties, which would give an exhaustive characteristic of its ability to interact with nAM.

Authors will be grateful to colleagues for any help in decision and discussion of these problems.