Metabolism of monocarbon compounds during biological purification of sewage waters]

Pathways and rates of metabolism of three 14C1-compounds (methanol, formaldehyde, and formic acid) were investigated by means of the heterogeneous population of activated sludge microorganisms. For the above microbial population formaldehyde was the primary or preferential substrate. During an hour aeration it was processed by activated sludge 6 times faster than by sodium formiate and 2 times faster than by methanol. The basic pathways of its transformation were oxidation via formiate to CO2 with its partial reutilization and direct incorporation into the sludge biomass via the primary formation of serine. An addition of methanol increased the incorporation of 14C-formadehyde into biomass and decreased the formation of free 14CO2. The main mechanism of the transformation of 14C-formiate in activated sludge was its oxidation to CO2. An addition of methanol and formaldehyde induced no essential changes in the rate or pattern of their metabolism.     

Relationship between micro- and minisatellites in the human genome

Micro- and minisatellites constitute an essential part of DNA with a low sequence complexity and carry several important functions. A search for tandem repeats in the human genome with a length of a repeat unit of up to 70 bp, including repeats with a great number of nucleotide substitutions, has been performed using the TaadeaSWAN program. It was shown that, for a considerable number of minisatellites with the length of the repeating unit of less than 25 nt, a shorter repeating motif can be distinguished in the sequence of this repeat, which often is similar to the sequence of minisatellites widely occurring in the human genome. A model of hierarchic origination of minisatellites in the human genome is suggested.     

Regular location of exon starts in collagen I and VII genes with periods comparable to nucleosome repeat lengths

Wavelet transform analysis revealed quasiperiodicity of exon starts in the genes for collagens of types I and VII. In the regions coding for the fibrillar part of the protein, the average sum length of an exon and the following intron was ～165 nt, i.e. close to the minimal nucleosome repeat length. Such quasiperiodic segments comprising 2–5 contiguous exon+intron pairs of similar length encompassed more than 50% of exons making the fibrillar part. We also observed regular disposition of exon starts in the nonfibrillar part of collagen VII, but with a different period of 227 nt.     

Application of noninteracting probes in the protein structure space for the construction of statistical potentials for atom-atom interactions

Some effects hindering the construction of knowledge-based potentials of atom-atom interactions in problems of biopolymer modeling have been considered. It was shown that some limitations are overcome by considering the distribution of distances between noninteracting probes in the protein structure space. It was shown that knowledge-based potentials thus constructed can be effectively used to analyze the hydration of protein atoms. Using this approach, it is possible to predict the structure water location in a protein globule and recognize the correctly folded protein structure among decoys.