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R P Khropycheva

Publications and source records attributed to R P Khropycheva.

4 recordsLinked to original sources
PubMed1992

[Hydrolysis of prolactin by a serine proteinase from mammary gland secretory cell mitochondria].

Mitochondrial proteinase isolated from secretory cells of the mammary gland of lactating rats able to hydrolyze 125I-labeled and native prolactin (PRL) has been studied. The enzyme represents a serine proteinase and is localized in the inner mitochondrial membrane. The molecular mass of the enzyme is 17-18 kDa, pH optimum is at 8.0-9.0. Partial purification of the enzyme has been carried out. The Km constant for 125I-PRL is equal to 10(-6) M, that for 2% hemoglobin is 1.2 x 10(-4) M. Analysis of products of rat and ovine PRL hydrolysis by proteinase using high performance liquid chromatography and PAAG electrophoresis revealed the formation of large-size fragments of the hormone. A possible role of proteinase in the mechanism of PRL action on mammary gland tissues is discussed.

Animals↗
PubMed1989

[The lysosomal pathway of prolactin degradation in the mammary gland: kinetics of prolactin hydrolysis by cathepsin D and the peptides formed thereby].

Some peculiarities of prolactin hydrolysis by rat mammary gland lysosomal proteinases were studied. It was demonstrated that at pH 3.0-3.7 the initial steps of prolactin hydrolysis are under control of cathepsin D. Cysteine cathepsins are responsible for the deep degradation of the peptides formed. The molecular mass of rat mammary gland cathepsin D as determined by chromatography on Sephadex G-100 is about 45 kDa. Using affinity chromatography on hemoglobin-Sepharose 4B, cathepsin D was purified 300--320-fold. The purified enzyme rapidly hydrolyzes low concentrations of prolactin down to peptides with Mr less than 1 kDa. At substrate--enzyme concentration ratios above 3:1, the limited proteolysis of prolactin occurred. At early steps of prolactin hydrolysis the formation of two peptides (Mr approximately 10 kDa) takes place. Deeper degradation of sheep prolactin led to the formation of four peptides with molecular masses of 6630, 3020, 1880 and 1040 Da (data from SDS-PAGE electrophoresis). An analysis of structural peculiarities of prolactin from different animal species revealed that this hormone is protected from the damaging effect of exopeptidases.

Amino Acid Sequence↗
PubMed1982

[Systemic vascular reactions to a decrease in volumetric blood flow velocity during artificial circulation].

In anesthetized cats with artificial circulation, a decrease in the systemic perfusion pressure (SPP) following reduction of the blood flow volume velocity evokes under conditions of weakly pulsating blood flow a constrictory response of neurogenic character which can be compensated for by an opposite myogenic response in conditions of pulsating blood flow. These differences only occur at a high enough initial level of the SPP. The myogenic component of regulation of the resistance vessels tonus seems to be suppressed in conditions of weakly pulsating blood flow. Questions bearing on regulation of the systemic hemodynamics, are discussed.

Animals↗