Preparation of subtilisin BPN' and dextran conjugates

The conditions for subtilishine BPN' binding with bromocyanogen activated dextranes have been selected. The dependence of the enzyme activity and stability from pH and temperature levels has been studied. The stability of a modified enzyme during storage in solution is increased as compared with that of the native enzyme due to a decrease in the autolysis rate. On the basis of diffusion coefficients and sedimentation constants of conjugates, absolute values of their molecular weights have been computed.     

Identity of human granulocyte kininogenase and plasminogen activator

Preparative isoelectrofocusing used for fractionating the whole human granulocyte lysate serine proteinases revealed multiple forms of elastase, cathepsin G, kininogenase, human granulocytes plasminogen activator (pI 6.2-10.75). Kinetic characteristics of their substrate specificity were also obtained. It is shown that serine kininogenase of human granulocytes is not identical with elastase as it had been supposed before, it is of trypsin-like nature and is identical with plasminogen activator of these cells. The results obtained reveal new aspects in comprehension of the role of the granulocyte plasminogen activator in development of the inflammatory reaction. It is found that acid-stable proteinase inhibitors formed from blood plasma inter-alpha-inhibitor of trypsin, have an inhibitory effect on the granulocyte plasminogen activator, that supports an assumption on the anti-inflammatory function of these inhibitors.     

Specific Features of the Photosynthetic System in the French Bean (Phaseolus vulgarisL.) in the Southern Moscow District

The main patterns of the functioning of the photosynthetic system of the French bean were established on the basis of comparative tests of eight cultivars and varieties. Some agrotechnical methods were developed which enhance the highest efficiency of the plant's photosynthetic activity. The data obtained are essential for the introduction of promising varieties of the bean cultures in the nonchernozem zone of Russia.     

What is Killing Organic Photovoltaics: Light‐Induced Crosslinking as a General Degradation Pathway of Organic Conjugated Molecules

In view of a rapid development and increase in efficiency of organic solar cells, reaching their long‐term operational stability represents now one of the main challenges to be addressed on the way toward commercialization of this photovoltaic technology. However, intrinsic degradation pathways occurring in organic solar cells under realistic operational conditions remain poorly understood. The light‐induced dimerization of the fullerene‐based acceptor materials discovered recently is considered to be one of the main causes for burn‐in degradation of organic solar cells. In this work, it is shown that not only the fullerene derivatives but also different types of conjugated polymers and small molecules undergo similar light‐induced crosslinking regardless of their chemical composition and structure. In the case of conjugated polymers, crosslinking of macromolecules leads to a rapid increase in their molecular weight and consequent loss of solubility, which can be revealed in a straightforward way by gel permeation chromatography analysis via a reduction/loss of signal and/or smaller retention times. Results of this work, thus, shift the paradigm of research in the field toward designing a new generation of organic absorbers with enhanced intrinsic photochemical stability in order to reach practically useful operation lifetimes required for successful commercialization of organic photovoltaics.     

Paedomorphosis as an Evolutionary Driving Force: Insights from Deep-Sea Brittle Stars

Heterochronic development has been proposed to have played an important role in the evolution of echinoderms. In the class Ophiuroidea, paedomorphosis (retention of juvenile characters into adulthood) has been documented in the families Ophiuridae and Ophiolepididae but not been investigated on a broader taxonomic scale. Historical errors, confusing juvenile stages with paedomorphic species, show the difficulties in correctly identifying the effects of heterochrony on development and evolution. This study presents a detailed analysis of 40 species with morphologies showing various degrees of juvenile appearance in late ontogeny. They are compared to a range of early ontogenetic stages from paedomorphic and non-paedomorphic species. Both quantitative and qualitative measurements are taken and analysed. The results suggest that strongly paedomorphic species are usually larger than other species at comparable developmental stage. The findings support recent notions of polyphyletic origin of the families Ophiuridae and Ophiolepididae. The importance of paedomorphosis and its correct recognition for the practice of taxonomy and phylogeny are emphasized.     

Alternative cyclization in GFP-like proteins family. The formation and structure of the chromophore of a purple chromoprotein from Anemonia sulcata

Anemonia sulcata purple protein (asFP595) belongs to a family of green fluorescent protein (GFP)-like proteins from the Anthozoa species. Similar to GFP, asFP595 apparently forms its chromophore by modifying amino acids within its polypeptide chain. Until now, the GFP-like proteins from Anthozoa were thought to contain chromophores with the same imidazolidinone core as GFP. Mass spectral analysis of a chromophore-containing tryptic pentapeptide from asFP595 demonstrates that chromophore formation in asFP595 is stoichiometrically the same as that in GFP: one H(2)O and two H(+) are released while a Schiff base and dehydrotyrosine are formed. However, structural studies of this asFP595 chromopeptide show that in contrast to GFP, the other peptide bond nitrogen and carbonyl carbon are required for chromophore cyclization, a reaction that yields the six-membered heterocycle 2-(4-hydroxybenzylidene)-6-hydroxy-2,5-dihydropyrazine. Spectrophotometric titration reveals three pH-dependent forms of the asFP595 chromopeptide: yellow (absorption maximum = 430 nm) at pH 3.0; red (absorption maximum = 535 nm) at pH 8.0; and colorless (absorption maximum = 380 nm) at pH 14.0. The pK(a) values for these spectral transitions (6.8 and 10.9) are consistent with the ionization of the phenolic group of dehydrotyrosine and deprotonation of the amidinium cation in the chromophore heterocycle, respectively. The amidinium group in asFP595 accounts for the unique absorption spectrum of the protein, which is substantially red-shifted relative to that of GFP. When the asFP595 chromophore cyclizes, the Cys-Met bond adjacent to the chromophore hydrolyzes, splitting the chromoprotein into 8- and 20-kDa fragments. High performance liquid chromatography analysis of a tryptic digest of denatured asFP595 shows that a pentapeptide with the cleaved Cys-Met bond is the only fragment associated with the red-shifted absorbance. These results imply that fragmentation of asFP595 is a critical step in protein maturation.     

Aggregation of C-reactive protein in solutions at acid pH

The hydrodynamic properties of the C-reactive protein (CRP) at different pH were studied using quasi-elastic light scattering, size-exclusion liquid chromatography, and nonreducing gel electrophoresis. It was shown that a CRP solution at pH 5.0-7.2 presents a polydisperse system the major component of which is the native pentameric CRP. At pH 4.0-4.5, CRP exists in two states having different hydrodynamic properties: the native pentameric form with a molecular mass of 120 kDa and with the hydrodynamic radius of 4.03 nm and high-molecular-weight aggregates with a wide range of their molecular weight distribution. The interaction of the C-reactive protein with monoclonal antibodies to it indicates that conformation-dependent surface epitopes of the protein lose the native structure at pH 5.0-5.5. The aggregation of CRP is an irreversible process, which begins in a narrow pH range of pH 5.0-4.5 and is not accompanied by the dissociation into subunits but is determined by intermolecular interactions of its quasi-native pentamers.     

Evaluation of the relevance of using RAPD-analysis for revealing the phylogenic connections between cultivars of drum wheat (T. durum Desf.)

A comparison of similarity indices between 64 durum wheat cultivars calculated using pedigree analysis and RAPD method showed a correspondence between these two approaches to estimation of genetic diversity. The associations between the results of RAPD clustering and coefficients of parentage (chi 2 test) and the coefficient of correlation between similarity matrices were statistically significant. However, the correlation was rather weak while pedigree analysis and RAPD method did not yield completely identical estimates of genetic diversity in the set of cultivars studied.     

Specific features of the HIV infection epidemic in Moscow

Retrospective analysis of the epidemic of HIV infection in Moscow allowed to mark out two periods: the first--from 1987 to 1993 and the second one--from 1994 to 2000. The characteristic feature of the first period of the epidemic was the sexual transmission of the agent mainly among homosexuals; the most affected group were persons aged 20-39 years and the number of AIDS patient decreased with a simultaneous growth in lethality. During the second stage of the HIV infection epidemic changes in the prevailing transmission routes of the agent occurred: injection drug addicts took the leading role. Changes in the ratio of HIV-infected men and women took place along with active involvement of persons aged 13-18 years into the epidemic process. The established changes in the epidemiological situation require corrections in the strategy and tactics of epidemic control and prophylactic measures.