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Biomedical subjects

N V Pushkina

Publications and source records attributed to N V Pushkina.

16 recordsLinked to original sources
PubMed1986

[Changes in the fluorescence in preparations of normal human immunoglobulin during deamidation].

It was shown that self-fluorescence of normal human immunoglobulins prepared with the use of donor and placental raw materials lowered after incubation at 37 degrees C for 28 days and after storage under the standard conditions (4-10 degrees C) for 2 years. Dependence of thermostability of the immunoglobulins on the raw material used for their preparation and the storage period was revealed spectrofluorometrically. Resistance of the proteins to thermal denaturation lowered on storage. However, it was higher in the immunoglobulins prepared with the use of donor serum. Thermostability and lowering of self-fluorescence of the proteins depended on the level of their amidization.

Blood↗
PubMed1984

[Posttranslational deamidation of crystalline lens proteins during animal aging].

The amide content of total proteins and protein fractions (alpha-, beta-, gamma-cristallins and albuminoid) from cortex and nuclear lens zones of cattle has been investigated. The amide content in proteins of cortex and nuclear lens of young animals (1,5-2 years old) is the same. The decrease of the amide content in the proteins of nuclear lenz zone of old animals (6-12 years old) is due to fraction of readily hydrolysed amides. The data obtained prove the posttranslational desamidation of lens proteins at ageing. beta-Cristallines--the proteins with the highest amides content is exposed to posttranslational desamidation most of all.

Aging↗
PubMed1978

[Nonenzymatic deamidation as a factor in protein aging].

Amidation of two protein fractions of brain, heart and liver of senite rats was found to decrease by 15--21% as compared with that of young animals. This decrease was shown to be due to unstable amide groups. Strong evidence is presented favouring the preposition that in proteins the unstable amide groups are those of asparagine and the stable ones those of glutamine. The possibility of the nonenzymatic deamidation of proteins was investigated. Deaminated proteins were found to be more easily attacked by proteinases which could be one of the possible ways of breakdown of aging proteins.

Aging↗
PubMedDate not supplied

[A modification of lactoferrin isolation method].

A modified method was developed to isolate lactoferrin from women's colostrum by means of ion-exchange chromatography on a Servacel CM-52 column and gel filtration on a Toyoperal HW-52 column. These changes simplified the basic method and decreased the length of the procedure without affecting the biological activity and purity of the preparation. The modified method can be recommended to produce lactoferrin suitable for the use as a pharmaceutical preparation and nutritional additive to milk substitutes.

Chromatography, Ion Exchange↗
PubMedDate not supplied

[Effect of non-enzymatic desamidation of gamma-globulin on its properties and biological activity].

During incubation of gamma-globulin preparations under conditions similar to physiological ones within 28 days (0.9% NaCl, pH 7.0, 37 degrees) as well as during storage at 3-10 degrees within 36 months gradual nonenzymatic deamidation of the protein occurred mainly due to hydrolysis of readily accessible amide groups (asparagine). Fluorescence of the preparations decreased gradually in the course of deamidation; it constituted for 82% of the initial value after incubation during 28 days. Immunological activity of the gamma-globulin, which lost 19.6% of amide groups, was decreased by 34%; alteration in the amidation by 45.1% was accompanied by a decrease in active antibodies concentration by 92.3%. Nonenzymatic deamidation may be responsible for conformational alterations and inactivation of gamma-globulin.

Amides↗
PubMedDate not supplied

[The effect of various chemical compounds and storage conditions on the rate of non-enzymatic deamidation of protein preparations].

The effect of different substances partly used as preservatives for the blood storage and at different stages of manufacturing of human blood preparations on the dynamics of nonenzymatic deamidation of commercial protein preparations and on their heat stability was being studied. Albumin and gamma-globulin preparations in the solutions of 60% glycerol, 60% ethylene glycol, 40% beta-alanine, aspartic and glutamic acids in physiological concentrations, 40% glucose and 40% sucrose after 2-hour thermal denaturation (100 degrees) were incubated under (or close to) physiological conditions (pH 7, 37 degrees) for 0.7; 14, 21, 28 and 90 days. The protein preparations in the saline were used as control. After precipitation of protein with TCA, the contents of free ammonia and TCA-soluble products were measured by the Lowry technique. The precipitate washed by organic solvents was used to determine the amide fractions. No reliable difference in increasing the TCA-soluble Folin-positive products was observed. All substances studied but glycerol sped up the deamidation of albumin and gamma-globulin preparations both during thermal denaturation and incubation. On the contrary, glycerol slowed down the deamidation of proteins. Possible reasons of the observed phenomena are discussed.

Deamination↗
PubMedDate not supplied

[Effect of starvation on the intensity of proteolysis and amidation of proteins in tissues of rats of different ages].

Rates of autolysis and degree of amidation of tissue proteins were studied in rats under conditions of ageing and after starvation during 7 days. Proteins with decreased content of amide groups accumulated in brain, liver tissues and skeletal muscles. This phenomenon occurred apparently due to decrease in the rate of protein autolysis observed in ageing. In testes, where the rate of protein autolysis was similar both in young and old animals, the protein amidation was not altered on the course of ageing. Under conditions of severe starvation activation of proteolysis was observed in cells. At the same time, the amide content was restored in liver and muscle proteins of old rats up to the level, estimated in tissues of young animals. These data suggest stimulation of selective degradation of the deamidated proteins. The activation of autolysis and normalization of the protein amide groups content were not observed in brain of old animals under conditions of starvation.

Aging↗
PubMedDate not supplied

[Amidation of blood proteins during hyperglycemia in experimental diabetes mellitus].

Rates of amidation of blood serum albumin and hemoglobin was studied in hyperglycemia developed during alloxan diabetes mellitus. Content of glucose in blood of the animals with diabetes exceeded 5.2-fold its level in blood of controls; amount of glycosylated hemoglobin was increased by 41.7%. Concentration of total, readily and hardly hydrolyzed amide groups was decreased in hemoglobin of the impaired animals by 13.1%, 17.6% and 10.4%, respectively, as compared with control group. The degree of blood serum albumin amidation was not altered. Hyperglycemia, accompanied by glycosylation of proteins, was the most probable cause of accelerated deamidation of hemoglobin. Participation of the protein deamidation in pathogenesis of diabetes mellitus is discussed.

Amides↗
PubMedDate not supplied

[Degradation of deamidated proteins by tissue proteinases].

The rate of native and deamidized serum albumin in vitro splitting by the brain, liver, kidney, testicle and spleen tissue proteinases was studied at pH 3.2, 4.8, 7.2 and 8.5. The deamidized preparation of serum albumin was obtained during its incubation under sterile conditions at 37 degrees C. The amount of amide groups in the process of protein incubation decreased by 19.4% mainly due to readily hydrolyzed asparagine groups. Desamidated serum albumin is splitted by tissue proteinases more intensively than native albumin. Intensity of the splitting depends on pH of the incubation medium and proteinase source. Specific proteolytic activity to desamidated serum albumin is shown to decrease in old rats as compared to young ones.

Animals↗
PubMedDate not supplied

[Protein amidation in the aging organism].

The role of protein amide groups was studied in the process of the organism ageing. It is shown that with ageing there occurs the asparagin deamidation in water-soluble and water-insolbule proteins of the rat brain, liver and heart. The glutamine content in the old rat tissues remains at the level determined in the young animal tissues. Tissue proteins of old rats are better substrates for protein--a complex of proteinases of a wide specificity that those of young animals. An increased attack of the old animals proteins by nonspecific proteinases is due to a decrease in their amidation degree during ageing.

Aging↗
PubMedDate not supplied

[Use of proteolytic enzyme inhibitors for stabilizing medicinal substances during storage].

The possibility of stabilizing medicinal preparations of protein nature using the inhibitor of proteolytic enzymes, contrical (Trasilol) has been studied. On long storage, free ammonia and products of protein fragmentation accumulated in protein preparations, and the degree of amidation was reduced. This led to the decrease in biological activity of immunoglobulins and insulin. Contrical produced a stabilizing effect irrespective of the nature of protein, and because of this may find an application in pharmacy.

Aprotinin↗
PubMedDate not supplied

[Spontaneous deamidation of gamma-globulin].

gamma-Globulin from human blood serum was incubated in thermostat at 37 degrees within 15, 30, 45, 60 and 72 days. Amount of readily and poorly hydrolyzed amide groups as well as an increase in amino acid content were estimated in the protein at zero time and at these periods. The sterility of the preparation was examined in each case. Spontaneous deamidation of gamma-globulin, observed during incubation, caused an increase in negative charge and altered electrophoretic mobility of the protein molecule. gamma-Globulin was attacked by prothelin more effectively as amount of amide groups was decreased in the protein. Spontaneous deamidation appears to be one of reasons of the protein molecules ageing.

Amides↗