Coenzyme reorientations in the active sites of aspartate aminotransferase isoenzymes studied by linear dichroism method

Cytosolic and mitochondrial pig heart aspartate aminotransferases (cAspAT and mAspAT) and chicken heart cAspAT have been oriented in a compressed slab of polyacrylamide gel and their linear dichroism LD spectra have been recorded. The coenzyme's tilt angles in the active sites of chicken cAspAT and pig mAspAT and their quasisubstrate complexes imitating catalytic intermediates have been computed. The computations are based on reduced linear dichroism values (delta A/A), the known directions of the transition dipole moments in the coenzyme ring and atomic coordinates of the coenzyme obtained by X-ray crystallography. It has been found that formation of the enzyme complex with glutarate and protonation of the internal pyridoxal-lysine aldimine induce reorientations of the coenzyme. As a result of protonation, the coenzyme ring tilts by 27 degrees in cAspAT and 13 degrees in mAspAT. Formation of the external aldimine with 2-methylaspartate is accompanied by tilting of the coenzyme ring by 44 degrees in cAspAT and 39 degrees in mAspAT. For the quinonoid complex with erythro-3-hydroxyaspartate, the tilt angles were found to be 63 degrees in cAspAT and 53 degrees in mAspAT. It is inferred that the basic features of the active site dynamics are similar in the three AspAT's studied. The differences in the coenzyme tilt angles between cAspAT and mAspAT may be linked to catalytic and structural peculiarities of the isoenzymes.     

Ossification of the posterior longitudinal ligament]

The authors described 21 patients aged 37 to 83 with ossification of the posterior longitudinal ligament (10 with ischemic myelopathy, 6 with aftermaths of a trauma of the cervical spine, and 5 with the radicular syndrome on the basis of vertebral osteochondrosis. X-ray signs of three types of ossification of the posterior longitudinal ligament were defined and specified: linear, curved and mixed. The linear type was more frequently observed in the cervical spine whereas the curved type was more frequent in the lumbar spine.     

Immobilization of antibiotics on a titanium surface

Immobilization of antibiotics on the surface of electrolytically oxidated titanium was tried. Transfer of the immobilized ampicillin into hardly soluble calcium ampicillate resulted in providing the coating with antimicrobial activity for 5 days. The quantity of the immobilized antibiotic determined polarographically amounted to 6.4.10(-3) mol per 1 m2 of the surface.     

On a Finding of the Polyphagous Pest,Coffee Bean Weevil Araecerus fasciculatus (DeG.) (Coleoptera,Anthribidae), in Natural Habitats of Different Regions of Southern Russia

Entomological Review - One specimen of the coffee bean weevil, Araecerus fasciculatus (DeGeer), was found in the region of Sochi on the Black Sea Coast of Krasnodar Territory. In the recent decade...     

Effect of Low-Frequency Pulsed Magnetic Field and Low-Level Laser Radiation on Oxidoreductase Activity and Growth of Fungi—Active Destructors of Polymer Materials

Microbiology - Effect of low-frequency pulsed magnetic field and of low-intensity laser radiation on mycelial fungi actively degrading various polymer materials was studied. These factors had a...     

The Convergence of Alzheimer’s Disease Pathogenesis Concepts

Molecular Biology - Advances in the research of molecular factors involved in the onset and progression of Alzheimer’s disease, have led to the creation of several pathogenesis concepts of...