Cytochromes c', that occur in methanotrophic, denitrifying and photosynthetic bacteria, form unusual proximal penta-coordinate NO complexes via a hexa-coordinate distal NO intermediate. Their NO binding properties are similar to those of the eukaryotic NO sensor, soluble guanylate cyclase, for which they provide a valuable structural model. Previous studies suggested that hydrogen bonding between the displaced proximal histidine (His120) ligand (following its dissociation from heme due to trans effects from the distally bound NO) and a conserved aspartate residue (Asp121) could play a key role in allowing proximal NO binding to occur. We have characterized three variants of Alcaligenes xylosoxidans cytochrome c' (AXCP) where Asp121 has been replaced by Ala, Ile and Gln, respectively. In all variants, hydrogen bonding between residue 121 and His120 is abolished yet 5-coordinate proximal NO species are still formed. Our data therefore demonstrate that the His120-Asp121 bond is not essential for proximal NO binding although it likely provides an energy minimum for the displaced His ligand. All variants have altered proximal pocket structure relative to native AXCP.
In this study, a total of 209 individuals of leeches were collected from Al-Hindyia River / Babil Province. 116 individuals were identified as Erpobdella octaculata (Linnaeus, 1758), 50 individuals as Erpobdella punctata (Leidy,1870) and 43 individuals as Hemiclepsis marginata (Müller, 1774). Four samples were collected monthly during a period from February to June 2018. Some physical and chemical water properties were also examined, including air and water temperature, potential of hydrogen pH, Electrical Conductivity EC, Total Dissolved Solid TDS, Dissolved Oxygen DO, and the Biological Oxygen Demand BOD₅. Air and water temperature were ranged 19.5-29, & 14.6-23.2 °C respectively. The values of pH ranged 6.2-7.6. EC ranged 1104-1581 μs/cm². The TDS recorded 669-767 mg/l, while the DO reached 1.3-8.5 mg / l, the BOD₅ ranged 3.5-5.7 mg/l.
Background: A common 2548G/A promoter variant of the human leptin gene has been implicated in circulating leptin levels variations and pathogenesis of type 2 diabetes mellitus but available data are still conflicting. Objective: To explore potential associations between LEP 2548G/A of leptin with T2DM and the effect of this variation on serum leptin levels. Patients and Methods: Sixty two patients with T2DM and fifty non-diabetic controls were included in the study. Blood samples were collected from subjects for biochemical analysis and Genotyping was performed by polymerase chain reaction reaction-restriction fragment length polymorphism (PCR-RFLP). Results: The genotype frequencies for LEP 2548G/G, LEP 2548G/A LEP 2548A/A were 46%, 32% and 22% in control group, and 19.4%, 33.9% and 46.7% in diabetic group, respectively. The A allele and GA/AA genotype of LEP 2548G/A was found to be more frequent than the G allele and GG genotype in T2DM patients compares to the controls. Subjects with the GA + AA genotype of LEP 2548G/A were at increased risk for T2DM (P=0.0001, OR = 1.78; 95% CI: 1.19-2.38). The serum leptin concentration of GA + AA genotype carriers was significantly higher from that of the GG genotype in the diabetic group.
Conclusion:A allele carrier who have higher serum concentrations of leptin may have an association with the risk of T2DM development in the Erbi population.
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