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L V Abaturov

Publications and source records attributed to L V Abaturov.

At least 19 recordsLinked to original sources
PubMed1985

Compact state of a protein molecule with pronounced small-scale mobility: bovine alpha-lactalbumin.

We describe a novel physical state of a protein molecule which is nearly as compact as the native state and has pronounced secondary structure, but differs from the native state by the large increase of thermal fluctuations (in particular, by the large mobility of side groups). This state has been characterized in detail for the acid form of bovine alpha-lactalbumin as a result of the study of physical properties of this state by a large variety of different methods (hydrodynamics, diffuse X-ray scattering, circular dichroism and infrared spectra, polarization of the luminescence, proton magnetic resonance, deuterium exchange and microcalorimetry). It has been shown that bovine alpha-lactalbumin can be transformed into a similar state by thermal denaturation. This process is thermodynamically two state (i.e. all-or-none transition), which means that this state differs from the native one by a phase transition of the first order.

Animals↗
PubMedDate not supplied

[A comparative structure-function analysis and molecular mechanism of action of endonucleases from Serratia marcescens and Physarum polycephalum].

Structural and functional characteristics were compared for wild-type nuclease from Serratia marcescens, which belongs to the family of DNA/RNA nonspecific endonucleases, its mutational forms, and the nuclease I-PpoI from Physarum polycephalum, which is a representative of the Cys-His box-containing subgroup of the superfamily of extremely specific intron-encoded homing DNases. Despite the lack of sequence homology and the overall different topology of the Serratia marcescens and I-PpoI nucleases, their active sites have a remarkable structural similarity. Both of them have a unique magnesium atom in the active site, which is a part of the coordinatively bonded water-magnesium complex involved in their catalytic acts. In the enzyme-substrate complexes, the Mg2+ ion is chelated by an Asp residue, coordinates two oxygen atoms of DNA, and stabilizes the transition state of the phosphate anion and 3'-OH group of the leaving nucleotide. A new mechanism of the phosphodiester bond cleavage, which is common for the Serratia marcescens and I-PpoI nucleases and differs from the known functioning mechanism of the restriction and homing endonucleases, was proposed. It presumes a His residue as a general base for the activation of a non-cluster water molecule at the nucleophilic in line displacement of the 3'-leaving group. A strained metalloenzyme-substrate complex is formed during hydrolysis and relaxes to the initial state after the reaction. The English version of the paper.

Amino Acid Sequence↗
PubMedDate not supplied

[The conformational dynamic of the tetramer hemoglobin molecule as revealed by hydrogen exchange. I. Influence pH, temperature and ligand binding].

The rate of the H-D exchange of the peptide NH atoms of the different forms of human Hb was studied at the range of pH 5-10 and temperature 10-63 degrees C by the IR spectroscopy. The pH-dependence of the H-D exchange rate is accordance with the EX2 mechanism. Two pH-dependent conformers of ligand forms of Hb existes at 10-30 degrees C with lower probability of local fluctuations of the alkaline conformer. The difference between two conformers vanishes at 40 degrees C with the appearance of the third conformer with higher probability of local fluctuations. The deoxyHb at 20 degrees C and pH range 6-9 has no pH-dependent conformers and the probability of local fluctuations is considerably reduced in comparison to the acid conformer of ligand Hb. Upon the destabilization of the ligand Hb structure by the pH decreasing to 5.0 at 20 degrees C or the temperature increasing up to 50-60 degrees C at pH 7.1 the global fluctuations of the native structure are intensified providing the H-D exchange of the slowest exchanging NH atoms. The nature of the local and global fluctuations and possible similarity between the two pH-dependent conformers of ligand Hb and its functional R and R2 states revealed by the X-ray analysis and NMR spectroscopy were discussed.

Deuterium↗