Is the acid/base catalytic residue mutation in β- d -mannosidase Dt Man from Dictyoglomus thermophilum sufficient enough to provide thioglycoligase activity?

Biochimie ◽  
2017 ◽  
Vol 137 ◽  
pp. 190-196 ◽  
Author(s):  
Laure Guillotin ◽  
Nicolas Richet ◽  
Pierre Lafite ◽  
Richard Daniellou
Keyword(s):  
Catalytic Residue ◽  
Acid Base ◽  
Dictyoglomus Thermophilum

scholarly journals Structural bases for N-glycan processing by mannoside phosphorylase

2015 ◽  
Vol 71 (6) ◽  
pp. 1335-1346 ◽  
Author(s):  
Simon Ladevèze ◽  
Gianluca Cioci ◽  
Pierre Roblin ◽  
Lionel Mourey ◽  
Samuel Tranier ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structure Analysis ◽  
Single Step ◽  
Catalytic Residue ◽  
Acid Base ◽  
Human Gut ◽  
Main Determinants ◽  
Molecular Bases ◽  
Single Step Reaction ◽  
Glycan Degradation

The first crystal structure of Uhgb_MP, a β-1,4-mannopyranosyl-chitobiose phosphorylase belonging to the GH130 family which is involved in N-glycan degradation by human gut bacteria, was solved at 1.85 Å resolution in the apo form and in complex with mannose andN-acetylglucosamine. SAXS and crystal structure analysis revealed a hexameric structure, a specific feature of GH130 enzymes among other glycoside phosphorylases. Mapping of the −1 and +1 subsites in the presence of phosphate confirmed the conserved Asp104 as the general acid/base catalytic residue, which is in agreement with a single-step reaction mechanism involving Man O3assistance for proton transfer. Analysis of this structure, the first to be solved for a member of the GH130_2 subfamily, revealed Met67, Phe203 and the Gly121–Pro125 loop as the main determinants of the specificity of Uhgb_MP and its homologues towards the N-glycan core oligosaccharides and mannan, and the molecular bases of the key role played by GH130 enzymes in the catabolism of dietary fibre and host glycans.

scholarly journals The role of catalytic residue pKa on the hydrolysis/transglycosylation partition in family 3 β-glucosidases

2018 ◽  
Vol 16 (2) ◽  
pp. 316-324 ◽  
Author(s):  
Inacrist Geronimo ◽  
Christina M. Payne ◽  
Mats Sandgren
Keyword(s):  
Catalytic Residue ◽  
Acid Base ◽  
Potential Impact

The catalytic acid/base residue (E441) pKa, as modulated by its electrostatic environment, has potential impact on the hydrolysis/transglycosylation partition in β-glucosidases.

Higher Dietary Acidity is Associated with Lower Bone Mineral Density in Postmenopausal Iranian Women, Independent of Dietary Calcium Intake

2014 ◽  
Vol 84 (3-4) ◽  
pp. 0206-0217 ◽  
Author(s):  
Seyedeh-Elaheh Shariati-Bafghi ◽  
Elaheh Nosrat-Mirshekarlou ◽  
Mohsen Karamati ◽  
Bahram Rashidkhani
Keyword(s):  
Calcium Intake ◽  
Dietary Calcium ◽  
Dietary Calcium Intake ◽  
Dietary Intakes ◽  
Iranian Women ◽  
Acid Base Balance ◽  
Mineral Density ◽  
Acid Base ◽  
Base Balance ◽  
Dietary Acid

Findings of studies on the link between dietary acid-base balance and bone mass are relatively mixed. We examined the association between dietary acid-base balance and bone mineral density (BMD) in a sample of Iranian women, hypothesizing that a higher dietary acidity would be inversely associated with BMD, even when dietary calcium intake is adequate. In this cross-sectional study, lumbar spine and femoral neck BMDs of 151 postmenopausal women aged 50 - 85 years were measured using dual-energy x-ray absorptiometry. Dietary intakes were assessed using a validated food frequency questionnaire. Renal net acid excretion (RNAE), an estimate of acid-base balance, was then calculated indirectly from the diet using the formulae of Remer (based on dietary intakes of protein, phosphorus, potassium, and magnesium; RNAERemer) and Frassetto (based on dietary intakes of protein and potassium; RNAEFrassetto), and was energy adjusted by the residual method. After adjusting for potential confounders, multivariable adjusted means of the lumbar spine BMD of women in the highest tertiles of RNAERemer and RNAEFrassetto were significantly lower than those in the lowest tertiles (for RNAERemer: mean difference -0.084 g/cm2; P=0.007 and for RNAEFrassetto: mean difference - 0.088 g/cm2; P=0.004). Similar results were observed in a subgroup analysis of subjects with dietary calcium intake of >800 mg/day. In conclusion, a higher RNAE (i. e. more dietary acidity), which is associated with greater intake of acid-generating foods and lower intake of alkali-generating foods, may be involved in deteriorating the bone health of postmenopausal Iranian women, even in the context of adequate dietary calcium intake.

To Manage Infantile Hypertrophic Pyloric Stenosis by "Double-Y Pyloromyotomy" is a better Surgical Approach

2014 ◽  
Vol 1 (2) ◽  
pp. 143-147
Author(s):  
Md. Ansar Ali ◽  
Kaniz Hasina ◽  
Shahnoor Islam ◽  
Md. Ashraf Ul Huq ◽  
Md. Mahbub-Ul Alam ◽  
...  
Keyword(s):  
Weight Gain ◽  
Pyloric Stenosis ◽  
Hypertrophic Pyloric Stenosis ◽  
Treatment Modalities ◽  
Infantile Hypertrophic Pyloric Stenosis ◽  
Postoperative Vomiting ◽  
Acid Base ◽  
Feeding Regimes ◽  
Acid Base Status ◽  
Postoperative Feeding

Background: Different treatment modalities and procedures have been tried for the management of infantile hypertrophic pyloric stenosis. But surgery remains the mainstay for management of IHPS. Ramstedt’s pyloromyotomy was described almost over a hundred years ago and to date remains the surgical technique of choice. An alternative and better technique is the double-Y pyloromyotomy, which offer better results for management of this common condition.Methods: A prospective comparative interventional study of 40 patients with IHPS was carried out over a period of 2 years from July 2008 to July 2010. The patients were divided into 2 equal groups of 20 patients in each. The study was designed that all patients selected for study were optimized preoperatively regarding to hydration, acid-base status and electrolytes imbalance. All surgeries were performed after obtaining informed consent. Standard preoperative preparation and postoperative feeding regimes were used. The patients were operated on an alternate basis, i.e., one patient by Double-Y Pyloromyotomy(DY) and the next by aRamstedt’s Pyloromyotomy (RP). Data on patient demographics, operative time, anesthesia complications, postoperative complications including vomiting and weight gain were collected. Patients were followed up for a period of 3 months postoperatively. Statistical assessments were done by using t test.Results: From July 2008 through July 2010, fourty patients were finally analyzed for this study. Any statistical differences were observed in patient population regarding age, sex, weight at presentation, symptoms and clinical condition including electrolytes imbalance and acid-base status were recorded. Significant differences were found in postoperative vomiting and weight gain. Data of post operative vomiting and weight gain in both groups were collected. Vomiting in double-Y(DY) pyloromyotomy group (1.21 ± 0.45days) vs Ramstedt’s pyloromyotomy (RP) group(3.03 ± 0.37days) p= 0.0001.Weight gain after 1st 10 days DY vs RP is ( 298 ± 57.94 gm vs193±19.8 gm p=0.0014), after 1 month (676.67±149.84 gm vs 466.67 ± 127.71 gm, p=0.0001), after 2months (741.33± 278.74 gm vs 490±80.62 gm, p=0.002) and after 3 months (582±36.01gm vs 453.33±51.64 gm, p=0.0001).No long-term complications were reported and no re-do yloromyotomy was needed.Conclusion: The double-Y pyloromyotomy seems to be a better technique for the surgical management of IHPS. It may offer a better functional outcome in term of postoperative vomiting and weight gain.DOI: http://dx.doi.org/10.3329/jpsb.v1i2.19532

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