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81.
82.
David Ashford Rajeev Menon Anthony K. Allen Albert Neuberger 《The Biochemical journal》1981,199(2):399-408
1. Modification of potato (Solanum tuberosum) lectin with acetic anhydride blocked 5.1 amino and 2.7 tyrosyl groups per molecule of lectin and decreased the haemagglutinating activity of the lectin. De-O-acetylation regenerated 2.0 of the tyrosyl groups and resulted in a recovery of activity. 2. Modification with citraconic anhydride or cyclohexane-1,2-dione did not greatly affect activity, although modification of amino and arginyl groups could be demonstrated. 3. Treatment with tetranitromethane nitrated 3.7 tyrosine residues per molecule of lectin with concomitant loss of activity. The presence of 0.1m-NN′N″-triacetylchitotriose (a potent inhibitor of the lectin) in the reaction medium protected all the tyrosyl residues from nitration and the lectin was fully active. 4. Modification of tryptophyl groups with 2-hydroxy-5-nitrobenzyl bromide and 2,3-dioxoindoline-5-sulphonic acid modified 0.9 and 2.6 residues per molecule of lectin respectively with a loss of activity in each case. Reaction of potato lectin with 2,3-dioxoindoline-5-sulphonic acid in the presence of inhibitor protected 2.4 residues of tryptophan from the reagent. Loss of haemagglutination activity was prevented under these conditions. 5. Reaction of carboxy groups, activated with carbodi-imide, with α-aminobutyric acid methyl ester led to the incorporation of 5.3 residues of the ester per molecule of lectin. Presence of inhibitor in this case, although protecting activity, did not prevent modification of carboxy groups; in fact an increase in the number of modified residues was seen. This effect could be imitated by performing the reaction in 8m-urea. In both cases the number of carboxy groups modified was close to the total number of free carboxy groups as determined by the method of Hoare & Koshland [(1967) J. Biol. Chem. 242, 2447–2453]. Guanidination of lysine residues after carboxy-group modification gave less homoarginine than did the unmodified lectin under the same conditions, suggesting the formation of intramolecular cross-links during carbodi-imide activation. 6. It is suggested from the results presented that amino, arginyl, methionyl, histidyl and carboxyl groups are not involved in the activity of the lectin and that tyrosyl and tryptophyl groups are very closely involved. These findings are similar to those reported for other proteins that bind N-acetylglucosamine oligomers and also fit the general trend in other lectins. 相似文献
83.
Soong-Hoon Kim Keith L. Constantine Gerald J. Duke Valentina Goldfarb John T. Hunt Stephen Johnson Kevin Kish Herbert E. Klei Patricia A. McDonnell William J. Metzler Luciano Mueller Michael A. Poss Craig R. Fairchild Rajeev S. Bhide 《Bioorganic & medicinal chemistry letters》2013,23(14):4107-4111
The design, synthesis and characterization of a phosphonate inhibitor of N-acetylneuraminate-9-phosphate phosphatase (HDHD4) is described. Compound 3, where the substrate C-9 oxygen was replaced with a nonlabile CH2 group, inhibits HDHD4 with a binding affinity (IC50 11 μM) in the range of the native substrate Neu5Ac-9-P (compound 1, Km 47 μM). Combined SAR, modeling and NMR studies are consistent with the phosphonate group in inhibitor 3 forming a stable complex with native Mg2+. In addition to this key interaction, the C-1 carboxylate of the sugar interacts with a cluster of basic residues, K141, R104 and R72. Comparative NMR studies of compounds 3 and 1 with Ca2+ and Mg2+ are indicative of a highly dynamic process in the active site for the HDHD4/Mg2+/3 complex. Possible explanations for this observation are discussed. 相似文献
84.
The genetic variability among accessions ofProsopis was determined using randomly amplified polymorphic DNA (RAPD) profiles. Similarities of profiles were determined using the algorithm of Jaccard, and UPGMA and neighbour joining trees were generated from the similarity data. The average similarity was highest among the accessions ofP. glandulosa (0.52 ± 0.18) and least in the accessions ofP. juliflora (0.37 ± 0.15), indicating that the latter species has greater diversity among accessions. Our observations suggest that RAPD analysis could help in identifying genetic variations among different accessions ofProsopis. 相似文献
85.
Hui Wang Pawan Khera Bingyan Huang Mei Yuan Ramesh Katam Weijian Zhuang Karen Harris‐Shultz Kim M. Moore Albert K. Culbreath Xinyou Zhang Rajeev K. Varshney Lianhui Xie Baozhu Guo 《植物学报(英文版)》2016,58(5):452-465
Cultivated peanut is grown worldwide as richsource of oil and protein. A broad genetic base is needed for cultivar improvement. The objectives of this study were to develop highly informative simple sequence repeat(SSR)markers and to assess the genetic diversity and population structure of peanut cultivars and breeding lines from different breeding programs in China, India and the US. A total of 111 SSR markers were selected for this study, resulting in a total of 472 alleles. The mean values of gene diversity and polymorphic information content(PIC) were 0.480 and 0.429, respectively.Country-wise analysis revealed that alleles per locus in three countries were similar. The mean gene diversity in the US,China and India was 0.363, 0.489 and 0.47 with an average PIC of 0.323, 0.43 and 0.412, respectively. Genetic analysis using the STRUCTURE divided these peanut lines into two populations(P_1, P_2), which was consistent with the dendrogram based on genetic distance(G_1, G_2) and the clustering of principal component analysis. The groupings were related to peanut market types and the geographic origin with a few admixtures. The results could be used by breeding programs to assess the genetic diversity of breeding materials to broaden the genetic base and for molecular genetics studies. 相似文献
86.
87.
88.
The intestines of freshly caught Saccobranchus fossilis (a freshwater fish that contains dehydroretinol) became free from carotenoids and from vitamin A when the fish were starved for about 20 days. When beta-carotene was administered to such fish, retinoic acid could be isolated from the intestines after approx. 4h. When lutein was administered to such fish, dehydroretinol and 3-hydroxyretinol could be isolated from the intestines after approx. 5h. 相似文献
89.
Bernd Haditsch Andreas Roessler Peter Krisper Herwig Frisch Helmut G. Hinghofer-Szalkay Nandu Goswami 《PloS one》2015,10(3)
Aims
We investigated changes in volume regulating hormones and renal function at high altitudes and across gender.Methodology
Included in this study were 28 subjects (n = 20 males; n = 8 females. ages: 19 – 65 yrs), who ascended to a height of 3440m (HA1), on the 3rd day and to 5050m (HA2), on the 14th day. Plasma and urinary creatinine and urinary osmolality as well as plasma levels of plasma renin activity (PRA), Aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP) were measured. The plasma volume loss (PVL) was estimated from plasma density and hematocrit. Glomerular filtration rate (GFR) was measured based on nocturnal (9 hour) creatinine clearance; this was compared with various methods for estimation of GFR.Results
The mean 24-hour urine production increased significantly in both sexes across the expedition. But PVL reached significance only in males. No changes in Na+ in plasma, urine or its fractional excretion were seen at both altitudes. Urinary osmolality decreased upon ascent to the higher altitudes. ADH and PRA decreased significantly at both altitudes in males but only at HA2 in females. However, no changes in aldosterone were seen across the sexes and at different altitudes. ANP increased significantly only in males during the expedition. GFR, derived from 9-h creatinine clearance (CreaCl), decreased in both sexes at HA1 but remained stable at HA2. Conventional Crea[p]-based GFR estimates (eGFR) showed only poor correlation to CreaCl.Conclusions
We report details of changes in hormonal patterns across high altitude sojourn. To our knowledge we are not aware of any study that has examined these hormones in same subjects and across gender during high altitude sojourn. Our results also suggest that depending on the estimation formula used, eGFR underestimated the observed decrease in renal function measured by CreaCl, thus opening the debate regarding the use of estimated glomerular filtration rates at high altitudes. 相似文献90.
David J. Wilkinson George S. Bethell Rajeev Shukla Simon E. Kenny David H. Edgar 《PloS one》2015,10(5)
Enteric nervous system progenitor cells isolated from postnatal human gut and cultured as neurospheres can then be transplanted into aganglionic gut to restore normal patterns of contractility. These progenitor cells may be of future use to treat patients with Hirschprung’s disease, a congenital condition characterized by hindgut dysmotility due to the lack of enteric nervous system ganglia. Here we demonstrate that progenitor cells can also be isolated from aganglionic gut removed during corrective surgery for Hirschsprung’s disease. Although the enteric nervous system marker calretinin is not expressed in the aganglionic gut region, de novo expression is initiated in cultured neurosphere cells isolated from aganglionic Hirschsprung bowel. Furthermore, expression of the neural markers NOS, VIP and GFAP also increased during culture of aganglionic gut neurospheres which we show can be transplantation into cultured embryonic mouse gut explants to restore a normal frequency of contractility. To determine the origin of the progenitor cells in aganglionic region, we used fluorescence-activated cell sorting to demonstrate that only p75-positive neural crest-derived cells present in the thickened nerve trunks characteristic of the aganglionic region of Hirschsprung gut gave rise to neurons in culture. The derivation of enteric nervous system progenitors in the aganglionic gut region of Hirschprung’s patients not only means that this tissue is a potential source of cells for future autologous transplantation, but it also raises the possibility of inducing the differentiation of these endogenous cells in situ to compensate for the aganglionosis. 相似文献