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11.
He SM Wathier M Podzelinska K Wong M McSorley FR Asfaw A Hove-Jensen B Jia Z Zechel DL 《Biochemistry》2011,50(40):8603-8615
PhnP is a phosphodiesterase that plays an important role within the bacterial carbon-phosphorus lyase (CP-lyase) pathway by recycling a "dead-end" intermediate, 5-phospho-α-d-ribosyl 1,2-cyclic phosphate, that is formed during organophosphonate catabolism. As a member of the metallo-β-lactamase superfamily, PhnP is most homologous in sequence and structure to tRNase Z phosphodiesterases. X-ray structural analysis of PhnP complexed with orthovanadate to 1.5 ? resolution revealed this inhibitor bound in a tetrahedral geometry by the two catalytic manganese ions and the putative general acid residue H200. Guided by this structure, we probed the contributions of first- and second-sphere active site residues to catalysis and metal ion binding by site-directed mutagenesis, kinetic analysis, and ICP-MS. Alteration of H200 to alanine resulted in a 6-33-fold decrease in k(cat)/K(M) with substituted methyl phenylphosphate diesters with leaving group pK(a) values ranging from 4 to 8.4. With bis(p-nitrophenyl)phosphate as a substrate, there was a 10-fold decrease in k(cat)/K(M), primarily the result of a large increase in K(M). Moreover, the nickel ion-activated H200A PhnP displayed a bell-shaped pH dependence for k(cat)/K(M) with pK(a) values (pK(a1) = 6.3; pK(a2) = 7.8) that were comparable to those of the wild-type enzyme (pK(a1) = 6.5; pK(a2) = 7.8). Such modest effects are counter to what is expected for a general acid catalyst and suggest an alternate role for H200 in this enzyme. A Br?nsted analysis of the PhnP reaction with a series of substituted phenyl methyl phosphate esters yielded a linear correlation, a β(lg) of -1.06 ± 0.1, and a Leffler α value of 0.61, consistent with a synchronous transition state for phosphoryl transfer. On the basis of these data, we propose a mechanism for PhnP. 相似文献
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A new hominid parietal from Bodo, Middle Awash Valley, Ethiopia 总被引:2,自引:0,他引:2
B Asfaw 《American journal of physical anthropology》1983,61(3):367-371
A piece of left parietal of a Middle Pleistocene hominid, recovered from the Upper Bodo Sand Unit, in the Middle Awash, Ethiopia, is described anatomically and compared to Middle Pleistocene hominids and modern Homo sapiens. It bears several primitive features and has important implications for the original Bodo skull, found at the same stratigraphic level in the same area. The new fossil skull represents a different individual from the original Bodo skull. 相似文献
14.
Gebremedhin Gebrezgabiher Gebremedhin Romha Eyasu Ejeta Getahun Asebe Endalew Zemene Gobena Ameni 《PloS one》2016,11(2)
Tuberculosis (TB) is one of the major public health and socio-economic issues in the 21st century globally. Assessment of TB treatment outcomes, and monitoring and evaluation of its risk factors in Directly Observed Treatment Short Course (DOTS) are among the major indicators of the performance of a national TB control program. Hence, this institution-based retrospective study was conducted to determine the treatment outcome of TB patients and investigate factors associated with unsuccessful outcome at Dilla University Referral Hospital, southern Ethiopia. Five years (2008 to 2013) TB record of TB clinic of the hospital was reviewed. A total 1537 registered TB patients with complete information were included. Of these, 942 (61.3%) were male, 1015 (66%) were from rural areas, 544 (35.4%) were smear positive pulmonary TB (PTB+), 816 (53.1%) were smear negative pulmonary TB (PTB-) and 177(11.5%) were extra pulmonary TB (EPTB) patients. Records of the 1537 TB patients showed that 181 (11.8%) were cured, 1129(73.5%) completed treatment, 171 (11.1%) defaulted, 52 (3.4%) died and 4 (0.3%) had treatment failure. The overall mean treatment success rate of the TB patients was 85.2%. The treatment success rate of the TB patients increased from 80.5% in September 2008-August 2009 to 84.8% in September 2012–May 2013. Tuberculosis type, age, residence and year of treatment were significantly associated with unsuccessful treatment outcome. The risk of unsuccessful outcome was significantly higher among TB patients from rural areas (AOR = 1.63, 95% CI: 1.21–2.20) compared to their urban counterparts. Unsuccessful treatment outcome was also observed in PTB- patients (AOR = 1.77, 95% CI: 1.26–2.50) and EPTB (AOR = 2.07, 95% CI: 1.28–3.37) compared to the PTB+ patients. In conclusion, it appears that DOTS have improved treatment success in the hospital during five years. Regular follow-up of patients with poor treatment outcome and provision of health information on TB treatment to patients from rural area is recommended. 相似文献
15.
Two fractions of high-molar-mass soluble neutral maltase-glucoamylase (G1 and G2) of distal small intestine of 18-day-old rats separated on Sepharose 4B differ in sialylation which is reflected in their pI values obtained by chromatofocusing. The major soluble G1 fraction shows eight sialylated peaks converted by neuraminidase into a single fraction eluted at pH 4.21. Fraction G2 is less sialylated and neuraminidase causes its pI shift to 4.36. The chromatofocusing pattern suggests that G1 contains more acidic and G2 more basic glycoforms than their membrane-bound counterpart. Presence of less acidic pI values in the soluble G1 fraction of 18-day-old rats than in that of 13-day-old rats indicates that developmental decrease of sialylation concerns not only membrane-bound but also the soluble membrane-type of maltase-glucoamylase. 相似文献
16.
Horseradish peroxidase in the presence of hydrogen peroxide (HRP/H2O2) oxidizes a carcinogenic non-aminoazo dye, 1-phenylazo-2-hydroxynaphthalene (Sudan I) to the ultimate carcinogen, which binds to calf thymus DNA. The principal product of Sudan I oxidation by the HRP/H2O2 system is the benzenediazonium ion. Minor products are hydroxy derivatives of Sudan I, in which the aromatic rings are hydroxylated. The principal oxidative product (the benzenediazonium ion) is responsible for the carcinogenicity of Sudan I, because this ion, formed from this azo dye, binds to DNA. 相似文献
17.
The genus Cycniopsis is reexamined. Generic and specific delimitation is discussed with respect to morphological characters, including seed structures studied by scanning electron microscopy. A hierarchical key to Cycniopsis and related genera is presented.
Two species are recognised, C. humifusa and C. humilis comb. nov. Several names are reduced to synonymy, and three lectotypes and one neotype are selected. Both species are illustrated, and a distribution map is provided. 相似文献
Two species are recognised, C. humifusa and C. humilis comb. nov. Several names are reduced to synonymy, and three lectotypes and one neotype are selected. Both species are illustrated, and a distribution map is provided. 相似文献
18.
Aserse AA Räsänen LA Assefa F Hailemariam A Lindström K 《Systematic and applied microbiology》2012,35(2):120-131
The diversity and phylogeny of 32 rhizobial strains isolated from nodules of common bean plants grown on 30 sites in Ethiopia were examined using AFLP fingerprinting and MLSA. Based on cluster analysis of AFLP fingerprints, test strains were grouped into six genomic clusters and six single positions. In a tree built from concatenated sequences of recA, glnII, rpoB and partial 16S rRNA genes, the strains were distributed into seven monophyletic groups. The strains in the groups B, D, E, G1 and G2 could be classified as Rhizobium phaseoli, R. etli, R. giardinii, Agrobacterium tumefaciens complex and A. radiobacter, respectively, whereas the strains in group C appeared to represent a novel species. R. phaseoli, R. etli, and the novel group were the major bean nodulating rhizobia in Ethiopia. The strains in group A were linked to R. leguminosarum species lineages but not resolved. Based on recA, rpoB and 16S rRNA genes sequences analysis, a single test strain was assigned as R. leucaenae. In the nodC tree the strains belonging to the major nodulating groups were clustered into two closely linked clades. They also had almost identical nifH gene sequences. The phylogenies of nodC and nifH genes of the strains belonging to R. leguminosarum, R. phaseoli, R. etli and the putative new species (collectively called R. leguminosarum species complex) were not consistent with the housekeeping genes, suggesting symbiotic genes have a common origin which is different from the core genome of the species and indicative of horizontal gene transfer among these rhizobia. 相似文献
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Tesfaye Hailemariam Bekalo Demissew Sebsebe Woodmatas Zemede Asfaw Woldemariam 《Journal of ethnobiology and ethnomedicine》2009,5(1):1-15