Properties of pig liver transketolase]

Some properties of homogeneous transketolase from pig liver were studied. It was shown that the pH optimum of the transketolase reaction lies within the range of 7.8--8.2. The isoelectric point is at pH 7.6--7.8. The molecular weight of transketolase is 138,000 +/- 3,000 as determined by the sedimentation equilibrium method and about 152,000 according to the data from gel filtration through Sephadex G-200. The enzyme molecule is a tetramer of the alpha 2 beta 2 type. The molecular weights of the alpha- and beta- subunits determined by polyacrylamide gel in the presence of sodium dodecyl sulfate are 52,000--56,000 and 27,000--29,000, respectively. Transketolase contains about two moles of TPP per mole of protein and does not require metal ions for its catalytic activity.     

The Linker Region Plays a Regulatory Role in Assembly and Activity of the Vps4 AAA ATPase

The AAA-type ATPase Vps4 functions with components of the ESCRT (endosomal sorting complex required for transport) machinery in membrane fission events that are essential for endosomal maturation, cytokinesis, and the formation of retroviruses. A key step in these events is the assembly of monomeric Vps4 into the active ATPase complex, which is aided in part by binding of Vps4 via its N-terminal MIT (microtubule interacting and trafficking) domain to its substrate ESCRT-III. We found that the 40-amino acid linker region between the MIT and the ATPase domain of Vps4 is not required for proper function but plays a role in regulating Vps4 assembly and ATPase activity. Deletion of the linker is expected to bring the MIT domains into close proximity to the central pore of the Vps4 complex. We propose that this localization of the MIT domain in linker-deleted Vps4 mimics a repositioning of the MIT domain normally caused by binding of Vps4 to ESCRT-III. This structure would allow the Vps4 complex to engage ESCRT-III subunits with both the pore and the MIT domain simultaneously, which might be essential for the ATP-driven disassembly of ESCRT-III.     

Identification of the Locus Associated with Diabetic Nephropathy in Type 1 Diabetes Mellitus

Polymorphic tetranucleotide microsatellites D3S1512, D3S1744, D3S1550, and D3S2326 were used to study the association of chromosome region 3q21–q25 neighboring the angiotensin II receptor type 1 gene (AT ₂ R1) with diabetic nephropathy (DN) in diabetes mellitus type 1 (DM1). Allele and genotype frequencies were compared for DM1 patients with (N = 39) or without (N = 62) DN. Fisher's exact test with Bonferroni's correction revealed significant differences in frequencies of two D3S2326 alleles, one D3S1512 allele, and one allele and one genotype of D3S1550. No significant difference was observed with D3S1744. Thus, region 3q21–q25 proved tightly associated with DN in ethnic Russians with DM1 from Moscow.     

Polymorphic Gene Markers of Lipid Metabolism Are Associated with Diabetic Nephropathy in Patients with Type 1 Diabetes Mellitus

In groups of type 1 diabetes mellitus patients with and without clinical signs of diabetic nephropathy (n = 62 and 68, respectively), a search was made for associations between diabetic nephropathy and the polymorphic marker ε2/ε3/ε4 of apolipoprotein E gene (APOE), I/D marker of apolipoprotein B gene (APOB), and Ser447Ter marker of lipoprotein lipase-encoding gene (LPL). The risk of diabetic nephropathy was higher in the carriers of allele ε3 and genotype ε3/ε3 of the polymorphic marker ε2/ε 3/ε4 of APOE gene as well as in the carriers of allele I and APOB genotype I/I gene (OR = 2.08 and 2.16; 1.91 and 2.11, respectively). Conversely, the carriers of allele D showed a reduced risk of this complication (OR = 0.52). No significant differences in distribution of alleles and genotypes of the polymorphic marker Ser447Ter of LPL gene were found between the groups. Our results indicate that the genes encoding two major components of lipid metabolism are involved in the development of diabetic nephropathy in patients with type 1 diabetes mellitus.__________Translated from Genetika, Vol. 41, No. 7, 2005, pp. 931–937.Original Russian Text Copyright © 2005 by Yakunina, Shestakova, Voron’ko, Vikulova, Savost’yanov, Chugunova, Shamkhalova, Dedov, Nosikov.     

Regulation of geochemical activity of microorganisms in a petroleum reservoir by injection of H<Subscript>2</Subscript>O<Subscript>2</Subscript> or water-air mixture

In the course of pilot trials of biotechnologies for the enhancement of oil recovery in formation waters of the Gangxi bed of the Dagang oil field (China), microbiological processes were investigated. The biotechnologies are based on injection into the petroleum reservoir of different oxygen sources (H₂O₂ solution or a water-air mixture) with nitrogen and phosphorus salts. The injection of water-air mixture with nitrogen and phosphorus salts resulted in an increase in the number of aerobic and anaerobic organotrophic bacteria, rates of sulfate reduction and methanogenesis in formation water and also the content of CO₂ (from 4.8–12 to 15–23.2%) and methane (from 86–88 to 91.8%) in the gas. The preferential consumption of isotopically light bicarbonate by methanogens resulted in a higher content of the light ¹²C in methane; the δ¹³C/CH₄ value changed from ?45.1…?48.3 to ?50.7…?59.3‰. At the same time, mineral carbonates of the formation water became isotopically heavier; the δ¹³C/Σcarbonates value increased from 3.4…4.0 to 5.4…9.6‰. Growth of hydrocarbon-oxidizing bacteria was accompanied by production of biosurfactants and decreased interfacial tension of formation water. Injection of H₂O₂ solution resulted in the activation of aerobic processes and in suppression of both sulfate reduction and methanogenesis. Methane content in the gas decreased from 86–88 to 75.7–79.8%, probably due to its consumption by methanotrophs. Due to consumption of isotopically light methane, the residual methane carbon became heavier, with the δ¹³C/CH₄ values from ?39.0 to ?44.3‰. At the same time, mineral carbonates of the formation water became isotopically considerably lighter; the δ¹³C/Σcarbonates value decreased from 5.4…9.6 to ?1.4…2.7‰. The additional amount of oil recovered during the trial of both variants of biotechnological treatment was 3819 t.     

Polymorphism of gene encoding vascular angiotensin II receptor and microangiopathies in patients with insulin-dependent diabetes mellitus

Polymorphism A1166C of the AT1R gene encoding angiotensin vascular receptor [replacement of C (cytosine) for A (adenine)) at position 1166] was compared in patients with insulin-dependent diabetes mellitus (IDDM) complicated by diabetic nephropathy (DN) and in noncomplicated patients (n = 27 and n = 41, respectively) and also in patients with IDDM complicated by diabetic retinopathy (DR) and in correspondent noncomplicated individuals (n = 30 and n = 44, respectively). The frequency of AT1R gene alleles and genotypes in patients with IDDM complicated by DN did not differ significantly from that observed in patients with noncomplicated IDDM. In contrast, in patients with IDDM complicated by retinopathy, a significant decrease in the content of A allele (68.3% against 82.6%) and a significant increase in the content of C allele (31.7% against 17.4%) was found as compared with the control group. Thus, in the Moscow population, A1166C polymorphism of the AT1R gene is not associated with diabetic renal complications but indeed associated with diabetic retinal complications. C allele is a risk factor of DR (the relative risk, RR, is equal to 2.17), and A allele is, in contrast, a protective factor against early retinopathy development (RR is equal to 0.49).