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ГоловнаРізне → Клініко-лабораторна оцінка перебігу вагітності при гіперфункції щитоподібної залози (автореферат) - Реферат

Клініко-лабораторна оцінка перебігу вагітності при гіперфункції щитоподібної залози (автореферат) - Реферат

З'ясовано вплив режимів заморожування та –опромінення на діелектричні властивості сироватки кордової крові.

Розроблено алгоритм розрахунку коефіцієнтів деполяризації частинок складної форми та розраховано ефективну діелектричну проникність системи альбумін-вода.

Ключові слова: фібриноген, альбумін, гідратація, конформація, сироватка кордової крові, -опромінення, заморожування, НВЧ-діелектрометрія, діелектрична проникність, коефіцієнти деполяризації.


Горобченко О.А. Влияние -облучения и температуры на конформацию белков крови. – Рукопись.

Диссертация на соискание ученой степени кандидата физико-математических наук по специальности 03.00.02 – биофизика. – Харьковский национальный университет им. В.Н. Каразина, Харьков, 2005.

В диссертационной работе исследовано влияние -облучения и температуры на конформацию альбумина и фибриногена и на диэлектрические свойства сыворотки кордовой крови. Методом СВЧ-диэлектрометрии получены значения комплексной диэлектрической проницаемости водных растворов сывороточного альбумина и фибриногена в зависимости от дозы -облучения, температуры и концентрации белков в растворе. Получены значения времени диэлектрической релаксации молекул воды в растворах этих белков и в сыворотке кордовой крови. Рассчитаны значения гидратации альбумина и фибриногена. С помощью метода ЭПР получены спектры спиновых меток, ковалентно присоединенных к молекуле сывороточного альбумина. Установлено, что при облучении дозой 100 Гр происходит разрыхление поверхности белка в области присоединения слабо заторможенного радикала.

Установлено влияние режимов замораживания и –облучения на диэлектрические свойства сыворотки кордовой крови.

Разработан алгоритм расчета коэффициентов деполяризации частиц сложной формы и рассчитана эффективная диэлектрическая проницаемость системы вода-альбумин.

Ключевые слова: фибриноген, альбумин, гидратация, конформация, сыворотка кордовой крови, -облучение, замораживание, СВЧ-диэлектрометрия, диэлектрическая проницаемость, коэффициенты деполяризации.


Gorobchenko O.O. Influence of -irradiation and temperature on the conformation of the blood proteins. - Manuscript.

Thesis for a candidate's degree by speciality 03.00.02 - biophysics. – V.N. Karazin Kharkov National University, Kharkiv, 2005.

In modern biophysics the performance of research on the influence of such physical factors as ionizing radiation and temperature on blood proteins conformation is an extremely important and urgent problem because of the using of -irradiation, high and low temperatures in various areas of medicine and biology. Such studies will enable to expand our understanding of the processes that occur on the influence of these physical factors on bioobjects. It will allow us to find out the optimal technologies of sterilization and preservation of biopreparations derived from human donor and cord blood with the maximum activity storage. Such kind of technologies will enable to create the strategic reserves of preparations and to use them for the clinical purposes.

Ability to undergo of conformation transitions and opportunity to change a three dimensional structure is an important property of macromolecules that defines their functioning. A structural state of macromolecules and their hydration extensively determine the function activity of protein and can change under effect of the various physical factors. Therefore the purpose of this work was the examination of the influence of -irradiation and temperature on conformation, hydration and dielectric properties of blood proteins. The aqueous solutions of bovine serum albumin (BSA), human serum albumin and human fibrinogen, and also cord blood serum (CBS) have been studied. The samples were -irradiated by a 60Co source. The serum was frozen by two regimens: slow freezing down to -20 °C at a rate of 1-2 °C/min and rapid freezing at a rate of 300-400 °C/min by immersion into liquid nitrogen (-196 °C). Thawing was performed on water bath at 40-42 °C. The native samples were taken as a control. In examination the high sensitive experimental methods of a resonator microwave dielectrometry and EPR-spectroscopy have been used. The calculation of protein hydration has been carried out by the method of the disperse system dielectric permittivity theory and the method of discrete approach.

The real ' and imaginary '' parts of the complex dielectric permittivity ε* = ε′ - ίε′′ of the serum albumin and fibrinogen in aqueous solutions at various concentrations irradiated with doses 5-200 Gy were measured by the microwave dielectric method at a frequency of 9,2 GHz within the temperature range of 4-70 °C. The corrections based on measurements of conductivity contribution were made for inorganic ions presence. It has been determined that the character of the thermal conformation changes of albumin and fibrinogen and also the water molecule dielectric relaxation time in solutions depend on protein concentration and radiation dose. For the first time it was revealed that at the temperatures 30-34 °C and 44-47 °C for serum albumin and at the temperatures 24 °C and 32 °C for fibrinogen there is the increasing of the protein hydration which can be caused by conformation transitions of the macromolecules.

The EPR-spectra of spin traps that covalently associated to a serum albumin molecule have been obtained. It has been found that irradiation of BSA by a dose 100 Gy causes the loosening of protein structure on macromolecule surface, which results in the increasing of BSA hydration. At a dose increasing up to 150 Gy and 200 Gy one observes the decrease of hydration and breaking of the radical that is on the surface of BSA macromolecule, which can be caused by their aggregation.

The investigation of dielectric property of -irradiated fibrinogen solutions shown that at the range of doses 5-200 Gy the value of ' varies in limits 1 % from quantity of ' of the control sample. The dielectric permittivity of ' with a radiation dose rising was reduced. However in the range of doses 30-60 Gy the nonmonotone magnification of ' was observed that can be caused by conformation transition of macromolecules of fibrinogen.

The influence of freezing regimens and -irradiation on CBS dielectric properties has been studied. The structural state of CBS macromolecules was studied in the temperature range from +40 °C up to +5 °C, i.e. on the initial stage of cooling. It was shown that the temperature dependence of the dielectric permittivity has complicated character. Nonmonotonous changes of ', '' and water molecules dielectric relaxation time at 7-9 °C, 16-20 °C, 26-28 °C and 36-38 °C for native and frozen samples of CBS have been revealed. Water molecule dielectric relaxation time is the parameter that characterizes the molecule mobility in very high frequency field and, consequently, the degree of their interaction with an environment. The structural disorders and conformation changes in serum component result in the difference in the free-bound water system ratio and are accompanied by the change in dielectric parameters. So it is reasonably safe to suggest that the observed changes in dielectric parameters values is associated with the thermotropic conformational changes of CBS macromolecules, which accompanied by an increase of hydration degree. The decrease of ' values was found at slow freezing down to -20 °C and after -irradiation by doses 50 and 100 Gy in comparison with the control and rapid freezing samples. It can be result in increasing of bound water amount in the system that may be the cause of change in conformation in CBS macromolecules.

The algorithm for calculation of the depolarization factors of the arbitrary shape particles by the method of discrete approach has been developed. The effective dielectric permittivity of the water-albumin disperse system was calculated. Is was shown that using in calculations of the depolarization factors of the real structure of serum albumin molecule which was built on the base of X-ray data more close to the experiment results than in case of approximating of a macromolecule by an ellipsoid of rotation.

Key words: serum albumin, fibrinogen, hydration, conformation, cord blood serum, -irradiation, microwave dielectrometry, dielectric permittivity, depolarization factors.

Наукове видання

ГОРОБЧЕНКО Ольга Олександрівна

"Вплив –опромінення і температури на конформацію білків крові"

Підписано до друку 27.01.2005 р. Формат 60х90 1/16

Друк офсетний. Умовн.-др. арк.. 1.0. Тираж 100 прим. Зам. № 67

ТОВ "Рейтинг"

м. Харків, вул. Сумська, 37.