A Diffusion-Based Approach to Geminate Recombination of Heme Proteins with Small Ligands

A model of postphotodissociative monomolecular (geminate) recombination of heme proteins with small ligands (NO, O2 or CO) is represented. The non-exponential decay with time for the probability to find a heme in unbound state is interpreted in terms of diffusion-like migration of ligabs physics/0212040 and between protein cavities. The temporal behavior for the probability is obtained from numerical simulation and specified by two parameters: the time \tau_{reb} of heme-ligand rebinding for the ligand localized inside the heme pocket and the time \tau_{esc} of ligand escape from the pocket. The model is applied in the analysis of available experimental data for geminate reoxygenation of human hemoglobin HbA. Our simulation is in good agreement with the measurements. The analysis shows that the variation in pH of the solution (6.0<pH<9.4) results in considerable changes for \tau_{reb} from 0.36 ns (at pH=8.5) up to 0.5 ns (pH=6.0) but effects slightly on the time \tau_{esc} (\tau_{esc} ~ 0.88 ns).Comment: 8 pages with 4 figures, submitted to Chem. Phy

Non-equivalence of a and b subunits within human hemoglobin in conformational relaxation and molecular oxygen rebinding

В работе изучены неэквивалентность субъединиц а и b в гемоглобине человека, конформационная релаксация и повторное связывание молекулярного кислорода

Meso-substituted cationic 3- and 4-N-Pyridylporphyrins and their Zn(II) derivatives for antibacterial photodynamic therapy

Photodynamic inactivation of microorganisms known as antibacterial photodynamic therapy (APDT) is one of the most promising and innovative approaches for the destruction of pathogenic microorganisms. Among the photosensitizers (PSs), compounds based on cationic porphyrins/ metalloporphyrins are most successfully used to inactivate microorganisms. Series of meso-substituted cationic pyridylporphyrins and metalloporphyrins with various peripheral groups in the third and fourth positions of the pyrrole ring have been synthesized in Armenia. The aim of this work was to determine and test the most effective cationic porphyrins and metalloporphyrins with high photoactivity against Gram negative and Gram positive microorganisms. It was shown that the synthesized cationic pyridylporphyrins/metalloporphyrins exhibit a high degree of phototoxicity towards both types of bacteria, including the methicillin-resistant S. aureus strain. Zinc complexes of porphyrins are more phototoxic than metal-free porphyrin analogs. The effectiveness of these Zn-metalloporphyrins on bacteria is consistent with the level of singlet oxygen generation. It was found that the high antibacterial activity of the studied cationic porphyrins/metalloporphyrins depends on four factors: The presence in the porphyrin macrocycle of a positive charge (+4), a central metal atom (Zn2+) and hydrophobic peripheral functional groups as well as high values of quantum yields of singlet oxygen. The results indicate that meso-substituted cationic pyridylporphyrins/metalloporphyrins can find wider application in photoinactivation of bacteria than anionic or neutral PSs usually used in APD

ВЫСОКОЧУВСТВИТЕЛЬНЫЕ ЛАЗЕРНЫЕ ФЛУОРОМЕТРЫ ДЛЯ БЛИЖНЕГО ИНФРАКРАСНОГО И ВИДИМОГО ДИАПАЗОНОВ

Laser spectrometers for registration of luminescent signals with nanosecond temporal resolution are presented. The versatile spectrometer is capable to operate with up to tenth of nanometer resolution in wide spectral range. The specialized spectrometer for singlet oxygen luminescence measuring in vitro and in vivo possesses unique sensitivity in the near infrared region. Experimental results confirming high technical capacities of the setups are presented.Представлены лазерные флуорометры, способные регистрировать сигналы люминесценции с наносекундным временным разрешением. Универсальный флуорометр позволяет работать в широком спектральном диапазоне с разрешением вплоть до десятых долей нанометра. Специализированный флуорометр для измерения свечения синглетного кислорода in vitro и in vivo обладает уникальной чувствительностью в ближней инфракрасной области. Приведены экспериментальные результаты, подтверждающие высокие технические возможности установок

HIGHLY SENSITIVE LASER SPECTROMETERS FOR NEAR INFRARED AND VISIBLE RANGES

Laser spectrometers for registration of luminescent signals with nanosecond temporal resolution are presented. The versatile spectrometer is capable to operate with up to tenth of nanometer resolution in wide spectral range. The specialized spectrometer for singlet oxygen luminescence measuring in vitro and in vivo possesses unique sensitivity in the near infrared region. Experimental results confirming high technical capacities of the setups are presented