[The study of actin in denervated skeletal muscles by microcalorimetry]. / Issledovanie aktina denervirovannykh skeletnykh myshts metodom mikrokalorimetrii.

Method of scanning calorimetry of intact and denervated F-actin shows a change in thermostability of protein after denervation.

[Circular dichroism of actin from denervated skeletal muscles]. / Krugovoi dikhroizm aktina denervirovannykh skeletnykh myshts.

Method of circular dichroism did not indicate any changes of the secondary structure of globular and fibrillar actin from denervated skeletal muscles. The matter that some conformational changes of the aromatic residues do in fact accompany denervation was confirmed by fluorescence studies but not by CD spectra.

Is there any difference between actins from intact and denervated muscles?

Various techniques have been used (UV absorbance and fluorescence spectroscopy, polarised UV fluorescence microscopy, viscosimetry, electrophoresis and isoelectric focusing, superprecipitation, etc.) As suggested by several parameters, denervation interferes with the structure of actin by producing local conformation changes in the region of aromatic residues near the sites responsible for actin-actin and actin-myosin interactions.

[Spectroscopic study of myosin from denervated rabbit muscles]. / Spektroskopicheskoe izuchenie miozina denervirovannykh myshts krolika.

Spectra of tryptophan UV-fluorescence and UV-absorption of myosin isolated 30 days after denervation of white skeletal muscles of rabbit were studied. It has been observed that fluorescence intensity of such myosin in the maximum decreases. This decrease becomes more pronounced after purification of protein from admixtures. It has been shown that after denervation the absorption at 260 nm increases, however, the difference disappears after myosin purification. The data obtained point to a change of myosin structural state after denervation.

[Changes in structural and functional properties of actin in denervated rabbit skeletal muscles]. / Izmenenie strukturno-funktsional'nykh svoistv aktina pri denervatsii skeletnykh myshts krolika.

Amino acid composition of actin from white skeletal muscles of the rabbit was studied 14 and 50 days after denervation. The content of valine, histidine and tyrosine was shown to decrease and that of lysine and leucine to increase on the 14th day following denervation. The content of these amino acids was almost normalised on the 50th day. In case of actin obtained from the contralateral leg similar but less pronounced changes were revealed. The results obtained are discussed as to the role played by some of amino acids in actin polymerization.

[Superprecipitation of synthetic actomyosin after denervation]. / Superpretsipitatsiia sinteticheskogo aktomiozina posle denervatsii.

Superprecipitation of synthetic actomyosin formed from intact myosin and actin extracted from rabbit white skeletal muscles after denervation was compared with that of intact synthetic actomyosin. Superprecipitation was characterized by two parameters: (1) the value of superprecipitation delta E determining an increase in the absorption from minimum to maximum values, and (2) the time required for the half-maximum increase (t1/2) which is inverse of the velocity constant. It was shown that delta E and the velocity constant decrease and t1/2 after denervation. It is assumed that this effect is related to the changes in actin structure.

Effect of denervation on the properties of actin (according to superprecipitation data).

The superprecipitation of synthetic actomyosin, formed from intact myosin and actin extracted from rabbit white skeletal muscles 14 and 75 days after denervation has been compared with that of intact synthetic actomyosin. Superprecipitation has been characterized by two parameters. 1. The value of superprecipitation delta E determining the increase in the absorbance from minimum to maximum values; 2. the time required for the half-maximum increase (t 1/2) which is the inverse of the velocity constant. It has been shown that both the delta E and the velocity constant decrease: the delta E amounts to 75.4 +/- 7.3 per cent (p = 0.95) and 87.9 +/- 11.2 per cent (p = 0.95) after 14 and 75 days, respectively, when compared with normal; the t 1/2 increases to 41.5 +/- 13.6 per cent (p = 0.95) after 14 days and 17.5 +/- 11.9 per cent (p = 0.95) after 75 days. It is assumed that this effect is related to changes in the structure of actin.

The effect of denervation upon the functional properties of myosin and its fragments.

A study has been made of some structural and enzymatic properties of myosin and its fragments from denervated white muscles of rabbit in the course of atrophy using different methods: UV-luminiscence, flow birefringence, electromicroscopy, viscosimetry and enzymatic measurements. All the studied parameters had a tendency to decrease; at prolonged observation some properties were partially restored. Considerable changes of structural properties of LMM were revealed: the ability of LMM from denervated muscle to form high-ordered structures which is characteristic of LMM from normal muscle decreased considerably.

[Letter: Effect of denervation on the anomalous behavior of acridine orange stained actin in solution]. / Vliianie denervatsii na anomal'noe povedenie okrashennogo akridinovym oranzhevym aktina v rastvore

Effect of superviscous state of AO stained actin in concentrated salts (KCI) significantly decreases two weeks after denervation. These changes of anomalous behaviour of stained action are partially reversible at the long time diasrophy. This phenomenon is suggested to be connected with the structural changes of "denervated" actin, which are reflected in the changes of protein electrostatic region.