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Soil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil invertebrate abundance coincide with patches of low concentrations of pollutants. For this aim, spatial analysis by distance indices (SADIE) was applied. Three valleys in Belogorye Nature Reserve were chosen. One valley faced the tailing pond to the north and the other two faced south-east or south-west. Two sampling plots were chosen in each valley, 60 m apart from each other. On every plot 16 soil cores were collected from a grid of 4 × 4 units with a 5-m distance between each sample unit. Each soil core had an area of 76 cm 2 and was 12-15 cm deep. All macroinvertebrates were hand-sorted and identified to family. Abundance of soil invertebrates was not controlled by patches of metal concentration in the soil. Epigaeic groups, like insects and other invertebrates inhabiting the litter layer, were not directly associated with local parameters of the soil. On the contrary, belowground invertebrate abundance (elaterid larvae and earthworms) showed significant dissociation with some heavy metal (Fe, Pb, Zn) concentrations in the soil. The patchiness of soil pollution may act as a leading factor of belowground soil invertebrate distribution. The spatial structure of animal populations in industrially transformed soils needs further research.

Quantum-chemical calculation of the energies of the electronic transitions and the electronic structures of the neutral and ionic species of the nucleic acids components in their ground and lower excited singlet and triplet rrr* and nrr* states has been carried out in the all-valence-electron approximation CNDO/.S. The results of the calculation allow one to identify the most photoreactive sites of the molecules and to consider the dependence of the location of these sites on the ionic state of the molecules. The calculated data are compared with our previous results obtained in a rr-electron approximation. The individual absorption spectra of various ionic and tautomeric species of the nucleic acids components obtained by us earlier have been decomposed into bands corresponding to separate electronic transitions. As a rule, there is a good agreement between the calculated data in the two approximations and the experimental results.At the present time study of the electronic structure of various ionic and tautomeric species of the nucleic bases and their analogs attracts increasing attention. Indeed, the structural and functional specificity of the nucleic acids is determined by the reactivity of their components, which in turn is essentially determined by electronic structure. However, until recently attention was paid mainly to the electronic structure of only neutral species of the nucleic bases in their ground state. Only a few ionic species of the nucleic bases were studied in some papers (see Refs. 1-3); a different quantum-chemical method or a parameter system was used in each of them.One of the possible reasons for the inadequate attention to the electronic structure of the ionic species of the pyrimidine and purine bases of the nucleic acids was lack of a sufficiently complete spectroscopic description, which hampered comparison of the calculated data with the experimental results. In this connection in 197 1 a systematic experimental-theoretical study of the uv-spectral properties and of the electronic structure of various ionic and tautomeric pyrimidine and purine nucleic

Using a spectrokinetic approach the absorption spectra of the short-lived transient products in the enzymatic reaction of the glutamate decarboxylase with natural substrate are determined for the first time. The quantum-chemical calculations of the electronic structure and spectra of various ionic species of numerous vitamin Bb derivatives allowed a hypothesis on the nature of the intermediate products detected to be suggested. A model of the enzyme functioning taking into account the charge equilibria and some electronic-conformational relations is proposed.The impressive current advances in enzymology are dependent, to a considerable degree, on the active attention to this branch of science on the part of investigators working in a variety of other fields. In fact, solution of the most topical problems in biomedical sciences cannot, at present, be achieved without a thorough understanding of the mechanisms of enzyme action.A large and very important group of enzymes are those requiring pyridoxal-5'-phosphate as cofactor and effecting a variety of transformations of amino acids in all types of organisms-the so-called PLP-enzymes [l]. A large number of studies have been devoted to the investigation of enzymes belonging to this group, with studies aiming at elucidation of the mechanism of enzymic transamination reactions as a predominant topic.As opposed to our previous communication [ 2 ] , where a tentative model was formulated for the mechanism of enzymatic a-amino acid decarboxylation, the present paper discusses the interaction of glutamate decarboxylase from Escherichia coli with its natural substrate, taking into consideration the charge equilibria of coenzyme and substrate. The electronic structures of some nonenzymatic (model) coenzyme-substrate complexes are discussed. A more correct assignment to possible intermediates is suggested for the absorption bands recorded by means of the stop-flow procedure. (In the earlier paper [2] the spectroscopic resolution rested on the assumption that all spectral changes at 420 nm and beyond this wavelength were due only to the decrease in amount of the "internal" Schiff base; this resulted in somewhat inexact evaluation of the long-wave band in the difference spectrum.) In addition, some general aspects of the catalytic action of pyridoxal enzymes will be discussed.It should be stated that in the postulations regarding the model of enzymatic decarboxylation, the electronic structure and total energy, in the ground state, of