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161.
The purpose of this study was to investigate the stabilizing action of polyols against various protein degradation mechanisms
(eg, aggregation, deamidation, oxidation), using a model protein lysozyme. Differential scanning calorimeter (DSC) was used
to measure the thermodynamic parameters, mid point transition temperature and calorimetric enthalpy, in order to evaluate
conformational stability. Enzyme activity assay was used to corroborate the DSC results. Mannitol, sucrose, lactose, glycerol,
and propylene glycol were used as polyols to stabilize lysozyme against aggregation, deamidation, and oxidation. Mannitol
was found to stabilize lysozyme against aggregation, sucrose against deamidation both at neutral pH and at acidic pH, and
lactose against oxidation. Stabilizers that provided greater conformational stability of lysozyme against various degradation
mechanisms also protected specific enzyme activity to a greater extent. It was concluded that DSC and bioassay could be valuable
tools for screening stabilizers in protein formulations. 相似文献
162.
Early effects of gibberellic acid on barley aleurone layers 总被引:4,自引:0,他引:4
163.
Parekkat Ramachandran Ragesh Tenzin Nyibum Bhutia Satish Ganta Ashok Kumar Singh 《Archives Of Phytopathology And Plant Protection》2016,49(1-4):19-30
Repellent, antifeedant and toxic effect of crude hexane extract of Ageratum conyzoides were investigated against Helicoverpa armigera. In orientation bioassay, the extract exhibited dose-dependent repellency against neonates. Extract significantly increased the mortality and decreased growth of different larval stages when administrated orally in artificial diet. EC50 value was at 0.11% for larval growth inhibition. Toxicity of the extract was manifested by high mortality of first instar larvae after 7 days of feeding on diet containing 0.05–0.4% of extract with LC50 of 0.17%. Under choice bioassay, extract showed strong antifeedant activity against fifth instar larvae with DI50 of 0.21%. In nutritional bioassay, extract significantly reduced RCR, RGR, ECI and ECD of fifth instar larvae with increased AD. When RGR were plotted against RCR, the growth efficiency of larvae fed on treated diet was significantly lower than the control fed larvae suggesting the antifeedant and toxic effect of extract. 相似文献
164.
Isolation and functional characterization of hydrocarbon emulsifying and solubilizing factors produced by a Pseudomonas species 总被引:1,自引:0,他引:1
Reddy PG Singh HD Pathak MG Bhagat SD Baruah JN 《Biotechnology and bioengineering》1983,25(2):387-401
Pseudomonas PG-1 cultivated on pristane produced in good amount a heat-stable polymeric substance which showed strong hydrocarbon emulsifying and solubilizing properties. The substance was isolated in crude form and was found to contain 34% protein, 16% carbohydrate, and 40% lipid. The hydrocarbon solubilizing activity of the isolate was strongly inhibited by EDTA but the chelating agent had no effect on the hydrocarbon emulsifying activity. Both activities of the isolate were strongly inhibited by chymotrypsin treatment indicating the importance of the protein moiety for its activity. Hydrocarbon solubilization by the isolate showed a certain degree of specificity to pristane in modest agitation generally used in microbial cultivation, but this specificity was lost by vigorous agitation in a Waring blender. It was proposed that in the first case, solubilization was effected by a solubilizing factor specific to pristane, whereas in the latter case, nonspecific solubilization occurred due to the action of the emulsifying factor. The rate of pristane solubilization by heat-treated culture broth under the conditions of agitation used in cultivation (rotary shaker, 120 rpm) was found to be ca. 750 mg L(-1) h(-1) which was much larger than the maximal pristane uptake rate of 170 mg L(-1) h(-1) observed during microbial growth on the substrate. It was concluded that hydrocarbon solubilization could satisfactorily account for the substrate uptake and growth. 相似文献
165.
D. Brady P. Nigam R. Marchant D. Singh A. P. McHale 《Bioprocess and biosystems engineering》1997,17(1):31-34
The thermotolerant, ethanol producing yeast strain, K. marxianus IMB3 was immobilized in calcium alginate containing magnetically responsive Fe3O4 particles. In these studies the β-galactosidase derived from K. marxianus IMB3 was immobilized onto the Fe3O4 particles prior to inclusion into the alginate matrix. Ethanol production by the immobilized microorganism in the presence of Fe3O4 reached a maximum of 16?g/L on 40?g/L lactose whereas prior immobilization of the enzyme to the particles and inclusion into the alginate matrix increased ethanol production to a maximum concentration of 18 g/L. When Mn2+ was incorporated into fermentations containing the immobilized enzyme in the alginate matrix, ethanol production increased further to a maximum concentration of 20?g/L. In addition, the behaviour of the magnetically responsive biocatalyst containing the co-immobilized enzyme was examined in a batch-fed system in the presence and absence of Mn2+. 相似文献
166.
Sivakumar Allur Subramaniyan Sunirmal Sheet Saravanakumar Balasubramaniam Swami Vetha Berwin Singh Dileep Reddy Rampa Sureshkumar Shanmugam 《Cell communication & adhesion》2018,24(1):19-32
The objective of this study was to synthesize and characterize novel polyurethane (PU)-nanofiber coated with l-arginine by electrospinning technique. This study determined whether l-arginine conjugated with PU-nanofiber could stimulate cell proliferation and prevent H2O2-induced cell death in satellite cells co-cultured with fibroblasts isolated from Hanwoo (Korean native cattle). Our results showed that l-arginine conjugated with PU nanofiber could reduce cytotoxicity of co-cultured satellite cells. Protein expression levels of bcl-2 were significantly upregulated whereas those of caspase-3 and caspase-7 were significantly downregulated in co-culture of satellite cells compared to those of monoculture cells after treatment with PU-nanofiber coated with l-arginine and which confirmed by Confocal microscope. These results suggest that co-culture of satellite cells with fibroblasts might be able to counter oxidative stress through translocation/penetration of antioxidant, collagen, and molecules secreted to satellite cells. Therefore, this nanofiber might be useful as a wound dressing in animals to counter oxidative stresses. 相似文献
167.
168.
Roy S Khanna V Mittra S Dhar A Singh S Mahajan DC Priyadarsiny P Davis JA Sattigeri J Saini KS Bansal VS 《Life sciences》2007,81(1):72-79
Thiazolidinediones (TZDs) are currently the most efficacious class of oral antidiabetics. However, they carry the burden of weight gain and haemodilution, which may lead to cardiovascular complications. The present study was designed to ascertain whether a combination of dipeptidyl peptidase IV (DPP IV) inhibitor with low dose of a thiazolidinedione absolves TZD associated weight gain and oedema without compromising its efficacy. In this study, we examined the efficacy and safety of lower dose (1 mg/kg/day) of rosiglitazone, a thiazolidinedione, in combination with 5 mg/kg/day dose of LAF-237 (vildagliptin), a known DPP IV inhibitor, in aged db/db mice after 14 days of treatment and compared the combination with therapeutic dose (10 mg/kg) of rosiglitazone. The combination therapy showed similar efficacy as that of 10 mg/kg/day rosiglitazone in lowering random blood glucose (53.8%, p<0.001 and 54.3%, p<0.001 respectively), AUC ((0-120) min) during oral glucose tolerance test (OGTT) (38.6 %, p<0.01; 38.3%, p<0.01 respectively) and triglyceride levels (63.9% and 61% respectively; p<0.01). Plasma active glucagon like peptide-1 (GLP-1) and insulin levels were found to be elevated significantly (p<0.01 and p<0.05 respectively) in both LAF-237 and combination treated groups following oral glucose load. LAF-237 alone had no effect on random glucose and glucose excursion during OGTT in severely diabetic db/db mice. Interestingly, the combination treatment showed no significant increase in body weight as compared to the robust weight gain by therapeutic dose of rosiglitazone. Rosiglitazone at 10 mg/kg/day showed significant reduction (p<0.05) in haematocrit, RBC count, haemoglobin pointing towards haemodilution associated with increased mRNA expression of Na(+), K(+)-ATPase-alpha and epithelial sodium channel gamma (ENaCgamma) in kidney. The combination therapy escaped these adverse effects. The results suggest that combination of DPP IV inhibitor with low dose of thiazolidinedione can interact synergistically to represent a therapeutic advantage for the clinical treatment of type 2 diabetes without the adverse effects of haemodilution and weight gain associated with thiazolidinediones. 相似文献
169.
170.
Vineet K. Singh Manisha Vaish Trintje R. Johansson Kyle R. Baum Robert P. Ring Saumya Singh Sanjay K. Shukla Jackob Moskovitz 《PloS one》2015,10(2)
Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus. 相似文献