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L I Mikhaĭlova

Publications and source records attributed to L I Mikhaĭlova.

At least 19 recordsLinked to original sources
PubMed1980

[Conformational changes of spin-labeled native and modified phosphorylase B].

The phosphorylase B labelled with 2,2,6,6-tetramethyl-piperidine-1-oxyl-4-iodacetamide (phosphorylase I) and with 2,2,6,6-tetramethyl-piperidine-1-oxyl-4-ethylmaleinimide (phosphorylase II) was studied. It was shown that label I is characterized by a greater mobility with respect to the protein as compared to label II. In spin-labelled preparations of phosphorylase B the 1,5--2,0 SH-groups of the enzyme monomer having no effect on the enzyme activity were modified. The effects of AMP, glucose-1-phosphate and glucose-6-phosphate on the EPR spectrum of phosphorylase I were studied. The greatest changes in the spectrum (especially in the high field line) were found to occur in the presence of glucose-6-phosphate. These changes are due to the increase in the degree of anisotropic spin rotation. The experimental and theoretical spectra allowing to determine the correlation time for the protein moiety (tau b = 160 ns) were shown to be similar. The local conformation changes were found to occur in the vicinity of one of the two label-bound SH-groups of phosphorylase I. The EPR spectra demonstrate the S-shaped dependence of mobility of phosphorylase I label on concentration of glucose-6-phosphate (0,1--10 mM). In the presence of AMP no S-shaped dependence is observed. Reduced NaBH4 phosphorylase I does not reveal the S-shaped dependence of the label mobility on concentration of glucose-6-phosphate. The degree of the label immobilization in the apo-phosphorylase I--pyridoxal-5-chloromethylphosphonate complex in the presence of glucose-6-phosphate and AMP is the same as in cholophosphorylase I; however, in contrast to the choloenzyme it does not depend on glucose-6-phosphate (0,1--10,0 mM). The changes in the mobility of the spin label of apophosphorylase I and its complex with the AMP analog--adenosine-5'-chloromethylphosphonate--during the choloenzyme reconstruction by pyridoxalphosphate are indicative of participation of AMP and the phosphate group of AMP in the formation of the enzyme active center.

Adenosine Monophosphate↗
PubMed1978

[Structural-functional analysis of the complex between phosphorylase B and adenosine-5'-chloromethylphosphonate].

A complex of phosphorylase B with a tritium-containing AMP analogue, adenosine-5'-chloromethylphosphonate, was obtained. It is found on the basis of the results of the determination of N- and C-terminal amino acids, amino acid composition and sequence, that the peptide 1, modified by adenosine-5'-chloromethylphosphonate, corresponds to the fragment 185-191 in the primary structure of phosphorylase B, and is probably located in the allosteric center of the enzyme. The peptide 2, which is bound with the AMP analogue and corresponds to the fragment 795-798, is suggested to be located at the site of binding the second AMP molecule. The arginine residue 184 is discussed as a possible functional amino acid protein interacting with 5'-phosphate AMP group.

Adenosine Monophosphate↗