Evaluation of Glycosyl Hydrolases in the Secretome of <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> and Saccharification of Alkali-Treated Rice Straw

A thermotolerant Aspergillus fumigatus strain isolated from composting pile of mixed industrial waste was found to produce a spectrum of cellulase and hemicellulases when cultured on rice straw solidified substrate. The two-dimensional electrophoresis (2DE) resolved the secretome into 57 distinct protein spots. The zymograms developed against 2DE gels identified the presence of three β-glucosidases and five CBHI/EGI isoforms in the secretome. The peptide mass fingerprinting of 17 protein spots by liquid chromatography mass spectrometry characterized the secretome into different glycosyl hydrolase families. The enzyme cocktail produced by A. fumigatus was capable of efficient hydrolysis of alkali pretreated rice straw (at 7% and 10% w/v) resulting in 95% and 91% saccharification, respectively.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Analysis of salt stress induced changes in Photosystem II heterogeneity by prompt fluorescence and delayed fluorescence in wheat (Triticum aestivum) leaves

In order to investigate changes in the heterogeneity of PSII, prompt fluorescence induction curves (PFIC) and delayed fluorescence induction curves (DFIC) were measured in wheat leaves after salt treatment. From these data, antenna heterogeneity and reducing side heterogeneity were estimated. Results show that antenna size, which is further differentiated into α, β and γ PSII centers, is changed under salt stress conditions. At higher salt concentration, there is a decrease in the number of α PSII centers with simultaneous increase in the amount of β and γ PSII centers. Another aspect of antenna heterogeneity is explained in terms of connectivity (or grouping) between PSII centers which did not change significantly under salt stress. Reducing side heterogeneity was assessed by both DFIC and PFIC and results show that a significant increase in the conversion of Q(B)-reducing centers to Q(B)-non-reducing centers is observed under salt stress.     

In silico targeting PAD4 for the treatment of rheumatoid arthritis

Structural Chemistry - Rheumatoid arthritis (RA) is an autoimmune disorder that causes chronic inflammation with periodic bursts of activity in multiple synovial joints which lead to irreversible...     

Interactions between oxovanadium (IV), glycylvaline and imidazoles: An aqueous potentiometric and spectroscopic study

Speciation has been determined in aqueous oxovanadium, glycylvaline and imidazoles at 25 ± 1°C and μ = 0.1M NaClO₄ using a combination of potentiometry, and visible and EPR spectroscopy. Results of potentiometric and spectroscopic methods are consistent. Calculations of stability constants have been made using the SCOGS computer program.     

Simultaneous quantification of withanolides in Withania somnifera by a validated high-performance thin-layer chromatographic method

This paper describes a sensitive, selective, specific, robust, and validated densitometric high-performance thin-layer chromatographic (HPTLC) method for the simultaneous determination of 3 key withanolides, namely, withaferin-A, 12-deoxywithastramonolide, and withanolide-A, in Ashwagandha (Withania somnifera) plant samples. The separation was performed on aluminum-backed silica gel 60F254 HPTLC plates using dichloromethane-methanol-acetone-diethyl ether (15 + 1 + 1 + 1, v/v/v/v) as the mobile phase. The withanolides were quantified by densitometry in the reflection/absorption mode at 230 nm. Precise and accurate quantification could be performed in the linear working concentration range of 66-330 ng/band with good correlation (r2 = 0.997, 0.999, and 0.996, respectively). The method was validated for recovery, precision, accuracy, robustness, limit of detection, limit of quantitation, and specificity according to International Conference on Harmonization guidelines. Specificity of quantification was confirmed using retention factor (Rf) values, UV-Vis spectral correlation, and electrospray ionization mass spectra of marker compounds in sample tracks.     

Condition based divergence in synthesis of tetrahydrobenzo[b]pyrans

Research on Chemical Intermediates - An environmentally benign novel strategy is developed for the synthesis of tetrahydrobenzo[b]pyrans by using thiamine mononitrate as a green catalyst, with the...     

Drug Surfactant and Polymer Mediated Acid Catalyzed Hydrolysis of Acetohydroxamic Acid

The effects of drug-surfactant and polymer on the acid hydrolysis of acetohydroxamic acid (AHA) have been studied at room temperature in 2% (v/v) dioxane medium. Kinetic data corresponding to the reaction with drug micelles are analyzed by using the pseudo-phase ion exchange model. The binding constant and first-order rate constant in micellar media in presence of AMYTP⁺-Drug, AMYTP⁺-β-Cyclodextrine, AMYTP⁺-SDS, AMYTP⁺-PEG, AMYTP⁺-TX-100, AMYTP⁺-CTAB, have been studied in 0.5 M HCl media.     

Tandem mass spectra of transition-metal ion adducts of glycosyl dithioacetals; distinction among stereoisomers

Electrospray ionization mass spectra of some glycosyl dithioacetals recorded in the presence of transition-metal chlorides, XCl2 (where X = Co, Mn and Zn), give abundant adduct ions such as [M+XCl]+ and [2M-H+X]+ and minor ions such as [M-H+X]+ and [2M+XCl]+. The tandem mass spectra of these adducts show characteristic elimination of neutral molecules such as H2O, HCl, EtSH, CH2O, C2H4O2/C2H4O. [M+XCl]+ ions fragment readily and the fragmentation appears to be stereochemically controlled as the relative abundances of the fragments are different for three stereoisomers. The added metal is lost as neutral molecules in the form of XCl(OH) and XCl(SEt). This is a predominant pathway in the ZnCl+ adducts. [2M+XCl]+ ions fragment preferentially by elimination of HCl, indicating strong metal interactions in the resulting dimeric [2M-H+X]+ ion. As there are several electron-rich centers in the molecule, the dimeric complex [2M-H+X]+ can have several structures and the observed fragmentations may reflect the sum of those of all these structures. The dimeric complexes fragment by elimination of neutral molecules leaving the dimeric interactions intact. The extent of fragmentation varies for the stereoisomers, leading to stereochemical differentiation.