Biomedical subjects
Publications and source records attributed to A V Mal'tsev.
The appearance of newly synthesized proteins in the total protein fraction of a cell-free protein-synthesizing system not containing ribosomes and mRNA and enriched with polyenzyme complexes of aminoacyl-tRNA synthetases and corresponding proteins is proved experimentally. For modeling of extraribosomal protein biosynthesis we proposed a molecular polyenzyme mechanism of protein biosynthesis on a protein matrix.
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The formation mechanism of amyloid peptides in normally functioning neuron and upon the development of amyloidosis resulting in neuron death is described. Amyloid peptides are formed by enzymatic processing of a large protein precursor and participate in intermolecular interactions after conformational rearrangements resulting in the formation of pathogenic structures. They enter into the cascade of molecular and cellular events leading to amyloidosis and death of nervous cells. These molecular events clarify the relation between the conformation and function of neuropathogenic peptides and the role of this relation in the development of pathology of differentiated neurons. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2006, vol. 32, no. 3; see also http://www.maik.ru.
A specific complex of protein-receptor with hormone, which had a sedimentation coefficient 3.8S, was formed in cell nuclei on incubation of endometrial tissue from pregnant woman with 3H-progestrone at 37 degrees C in vitro. In cell cytoplasm of endometrium the progesterone-protein complex was observed which sedimented at 6.8S and 4.2S. Progesterone was accumulated mainly in nuclei; lower concentrations of the hormone were found in cell cytoplasm of endometrium. Fractions of mitochondria, microsomes and ribosomes also bound the hormone but less distinct as compared with the nuclei. The formation of cytoplasmic complex of progesterone with protein-receptor occurred on incubation of endometrial cytoplasmic fraction with 3h-progesterone at 4 degrees C.
A conception on amyloidosis as a key factor of neuronal death in neurodegenerative diseases is stated. Experimental evidence is presented that amyloidosis is caused by alterations in the activity of a number of enzymes as well as conformational changes in pathogenic proteins. Arguments for amyloidosis as the universal biological mechanism of specific elimination of neurons showing changed metabolic and physiological status of cell differentiation are adduced. The final pattern of cell death seems to differ cardinally from that in both apoptosis and necrosis.
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The existence of macromolecules which specifically bind 3H-testosterone is demonstrated in the soluble fraction of human uterus endometrium. Testosterone receptors of endometrial cytosol are heterogenous and comprise the component with high affinity (Kd--2,9x10(-10) M) and low capacity (concentration of binding sites--0,5 pmoles per mg of protein) and the component with lower affinity and higher capacity (4x10(-9) M and 4 pmoles/mg of protein respectively). Incubation of sliced of endometrium at 37 (but not at 0 degrees) with 3H-testosterone results in the binding of the steroid by chromatin. On the other hand, testosterone-cytoplasmic receptor complex is able to associate with chromatin at 0 degrees. Chromatin did not bind free 3H-testosterone under these conditions. The existence of the receptor for testosterone in endometrial cells promoting its transport into the nucleus and binding with chromatin corroborates the previously shown specific action of testosterone on messenger RNA biogenesis in the uterus. Polyinductor model of regulation of gene expression in higher organisms by steroid hormones is discussed.
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Using analytical PAAG-electrophoresis two specific proteins, D1 and D2, were found in decidual tissue of pregnant women (6-12 weeks). These proteins were isolated and purified by means of ammonium sulfate saturation, chromatography on Sepharose 6B and ion exchange chromatography on DEAE 52 cellulose. The degree of purification of both D1 and D2 proteins was 100% and 81%, respectively. The both proteins were free of DNA, RNA and polysaccharides. The pI values of D1 and D2 proteins were at pH 5.6-6.0. According to gel electrophoresis on PAA-SDS-Na and gel filtration on Sepharose 6B, molecular weight of D1 protein was about 50,000-55,000 and of D2 protein--150,000-160,000 and 300,000-320,000, respectively. The specific decidual proteins D1 and D2 appear to be distinct from the so-called "pregnancy proteins" described previously.
As shown by polyacrylamide gel disc electrophoresis, 21 fractions of soluble proteins were found in human endometrium at the proliferative step, whereas the decidual tissue contained only 13 fractions. Two specific protein components D1 and D2 with molecular weight 52,000 and 150,000 daltons, respectively, were observed in the cytosol of decidual tissue. The decrease in quantitative spectrum of soluble proteins from decidual tissue was apparently related to its narrow specialization during the differentiation process.