Mathematical models of oxygen-binding function of human hemoglobin modified with nitrogen oxide, in conditions of the UV-irradiation
Voronezh state university, biology and soil-science faculty, department of biophysics and biotechnology, Russia, 394006, Voronezh, Universitetskaya sq., 1, tel. 8(4732)208586, fax 8(4732)208308, e-mail: Dr_Huixs@mail.ru1 pp.
Nitrogen oxide (NO) plays the important role in modulation of hemodynamic and oxygenation of human and animal tissues and organism. Researches of the influence of NO and UV-irradiation on functional properties of human hemoglobin and mathematical modeling of processes of interaction of intact and modified hemoglobin with O2 represent significant theoretical and practical interest. It has been revealing, that function of saturation of Hb by O2 submits to S-shaped dependence, which is described by Ferhulst equation:
where Y - a degree of saturation of Hb by O2, %;X - partial pressure of O2, mm Hg; a0, a1, a2, a3 - the factors subject to definition.
UV-irradiation in dozes 151 and 453 J/m2 does not cause basic change of character of dependence of function of saturation in comparison with not irradiated sample: the increase in speed of saturation process is marked.
Presence at researched samples HbNO in concentration 0,1; 1,0; 5,0 and 10,0 % resulted in essential updating oxygen-binding functions of hemoprotein. It has been revealed, that HbNO makes active the initial stage of oxygenation and weakens hem-hem interactions in molecule. Dissociation curves of the Hb modified with NO, are described polynoms of 4-th - 6-th degree depending on concentration of the modifying agent:
at n=6 for [HbNO]=0,1%, n=5 for [HbNO]=1,0%, n=4 for [HbNO]=5,0%, n=6 for [HbNO]=10,0%.
The influence of UV-radiation in dozes of 151 and 453 J/m2 on a mix containing 0,1 % of HbNO caused intensification of the initial oxygenation stage. The increasing of HbNO concentration in samples up to 1,0 - 10,0 % did not lead to the statistically authentic changes of parameters of hemoprotein oxygenation after UV-modification. However, saturation curves of UV-irradiated mixes HbO2 and HbNO (except for a mix of 10 % HbNO and 90 % HbO2, irradiated in a doze 453 J/m2) are described by the logistical equations, as well as oxygenation curves of native and photomodified HbO2:
Therefore, modification of oxygen-binding function at the influence of HbNO has convertible character and is corrected by UV-radiation.
Differences of settlement saturation parameters of samples of human hemoglobin from experimental data do not exceed 5 % that allows using the offered mathematical models in practice.