Microbial alcohol dehydrogenases: recent developments and applications in asymmetric synthesis.

Alcohol dehydrogenases are a well-known group of enzymes in the class of oxidoreductases that use electron transfer cofactors such as NAD(P)/NAD(P)H for oxidation or reduction reactions of alcohols or carbonyl compounds respectively. These enzymes are utilized mainly as purified enzymes and offer some advantages in terms of green chemistry. They are environmentally friendly and a sustainable alternative to traditional chemical synthesis of bulk and fine chemicals.

Role of key enzymes in the production of docosahexaenoic acid (DHA) by sp. T01.

Docosahexaenoic acid (DHA) is an essential dietary supplement that is highly coveted due to its benefits for human health. Extensive research has been conducted for the sustainable commercial production of DHA by various strains in thraustochytrid family due to the accumulation of higher lipid content in the cells. The current study is focused on improving DHA production by investigating various key enzymes like glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), and ATP-citrate lyase (ACL) involved in DHA production using sp.

Self-Assembled Inhalable Immunomodulatory Silk Fibroin Nanocarriers for Enhanced Drug Loading and Intracellular Antibacterial Activity.

In this study, a pH-induced self-assembly-based method has been developed to form silk fibroin nanoparticles (SFN-2) with a higher drug loading capacity (21.0 ± 2.1%) and cellular uptake than that of silk fibroin particles produced by a conventional desolvation method (SFN-1).

Imine reduction by an Ornithine cyclodeaminase/μ-crystallin homolog purified from ATCC 7330.

We report a stereospecific imine reductase from ATCC 7330 (CpIM1), a versatile biocatalyst and a rich source of highly stereospecific oxidoreductases. The recombinant gene was overexpressed in and the protein CpIM1 was purified to homogeneity. This protein belongs to the Ornithine cyclodeaminase/ μ-crystallin (OCD-Mu) family of proteins which has only a few characterized members.

Pharmacophore based approach to screen and evaluate novel Mycobacterium cell division inhibitors targeting FtsZ - A modelling and experimental study.

Tuberculosis, caused by Mycobacterium tuberculosis has been one of the primal afflictions to human, and owing to the current scenario of drug resistance, newer drugs, and alternate targets are required to mitigate the disease. FtsZ is a GTP hydrolyzing protein, conserved in prokaryotes that plays a central role in Z-ring formation during cell division cytokinesis stage. This study employs the use of pharmacophore models derived from two different datasets based on Mtb-FtsZ GTPase inhibition and whole cell antibacterial activity, to virtually screen and shortlist novel compounds from In-house small molecule library as Mtb-FtsZ inhibitors and evaluate their in-vitro and ex-vivo activity.

Production of bioactive cyclotides in somatic embryos of Viola odorata.

Viola odorata L. (Violaceae), an Indian medicinal plant, contains a plethora of cyclotides, which are a class of cyclic peptides derived from plants, possessing several applications. Somatic embryo culture of V.

Effects of organic and inorganic salts on docosahexaenoic acid (DHA) production by a locally isolated strain of sp. T01.

The traditional source for docosahexaenoic acid (DHA) i.e. fish oil is currently being replaced by microbial sources due to the unpleasant odor and the risk of chemical contamination of fish.

Phospholipid stabilized gold nanorods: towards improved colloidal stability and biocompatibility.

Biocompatible and colloidally stable gold nanorods (GNRs) with well-defined plasmonic properties are essential for biomedical and theranostic applications. The as-synthesized GNRs using the seed-mediated method are stabilized by the surfactant, cetyltrimethylammonium bromide (CTAB), which is known for its cytotoxicity in many cell lines. Biocompatible GNRs synthesized using known protocols exhibit some extent of cytotoxicity and colloidal instability because of the incomplete removal of CTAB.

Cyclotides from the Indian Medicinal Plant Viola odorata (Banafsha): Identification and Characterization.

Cyclotides are cyclic cystine knotted macrocyclic plant peptides that have several promising applications. This study was undertaken to detect and identify known and new cyclotides in Viola odorata, a commercially important medicinal plant, from three geographical locations in India. The number of cyclotides in the plant varied with the tissue (leaves, petioles, flowers, runners, and roots) and with geographical locations in India.

A carbonyl reductase from Candida parapsilosis ATCC 7330: substrate selectivity and enantiospecificity.

Candida parapsilosis ATCC 7330, a rich source of highly stereospecific oxidoreductases, catalyzes oxidation-reduction of a plethora of compounds yielding industrially important intermediates. An (S)-specific carbonyl reductase (SRED) purified and characterized from this yeast is reported here. (R)-Specific carbonyl reductase (CpCR) was reported by us earlier.

H-Bonding controls the emission properties of functionalized carbon nano-dots.

Bathochromic and hypsochromic shifts in the photo-luminescent spectra of doped and functionalized carbon nano-dots (CDs) arise due to the complex interaction between CDs and the solvent molecules around them. Nitrogen-functionalized carbon nano-dots (N-CDs) were synthesized from citric acid and urea using microwave assisted hydrothermal methods. Optical studies (absorption and photoluminescence) from the as-synthesized N-CDs were carried out in polar protic, aprotic and non-polar solvents.

Direct observation of redox reactions in Candida parapsilosis ATCC 7330 by Confocal microscopic studies.

Confocal microscopic studies with the resting cells of yeast, Candida parapsilosis ATCC 7330, a reportedly versatile biocatalyst for redox enzyme mediated preparation of optically pure secondary alcohols in high optical purities [enantiomeric excess (ee) up to >99%] and yields, revealed that the yeast cells had large vacuoles under the experimental conditions studied where the redox reaction takes place. A novel fluorescence method was developed using 1-(6-methoxynaphthalen-2-yl)ethanol to track the site of biotransformation within the cells. This alcohol, itself non-fluorescent, gets oxidized to produce a fluorescent ketone, 1-(6-methoxynaphthalen-2-yl)ethanone.

Whole resting cells vs. cell free extracts of Candida parapsilosis ATCC 7330 for the synthesis of gold nanoparticles.

The cell free extracts of Candida parapsilosis ATCC 7330 are more efficient than the whole resting cells of the yeast in the synthesis of directly usable gold nanoparticles as revealed by this systematic study. Cell free extracts yielded gold nanoparticles of hydrodynamic diameter (50-200 nm). In this study, the total protein concentration influences the nanofabrication and not only the reductase enzymes as originally thought.

Candida parapsilosis: A versatile biocatalyst for organic oxidation-reduction reactions.

This review highlights the importance of the biocatalyst, Candida parapsilosis for oxidation and reduction reactions of organic compounds and establishes its versatility to generate a variety of chiral synthons. Appropriately designed reactions using C. parapsilosis effect efficient catalysis of organic transformations such as deracemization, enantioselective reduction of prochiral ketones, imines, and kinetic resolution of racemic alcohols via selective oxidation.

Crystal structure of (E)-1,3-bis-(6-methoxy-naphthalen-2-yl)prop-2-en-1-one.

In the title compound, C25H20O3, the central -C(=O)-C=C- chain is disordered over two positions about the central C atom, with an occupancy ratio of 0.848 (6):0.152 (6).

A fourier transform infrared spectroscopy (FTIR) based assay for Candida parapsilosis ATCC 7330 mediated oxidation of aryl alcohols.

We present an FTIR based assay to monitor the whole cell mediated oxidation of aryl alcohols by measuring the characteristic IR absorption of the hydroxyl group [OH] of the substrate and the carbonyl group [CO] of the corresponding oxidized product. This method expedites the analysis of whole cell mediated catalysis which is usually done by GC and/or HPLC. The FTIR assay had linearity with R(2)≥0.

Biocatalytic deracemisation of aliphatic β-hydroxy esters: improving the enantioselectivity by optimisation of reaction parameters.

Optically pure aliphatic β-hydroxy esters were prepared from their racemates by deracemisation using the biocatalyst Candida parapsilosis ATCC 7330. High optical purity (up to >99 %) and good yields (up to 71 %) of the product secondary alcohols were obtained. This study highlights the importance of optimization of reaction conditions using ethyl-3-hydroxybutanoate as the model substrate to improve the enantioselectivity (enantiomeric excess from 9 to 98 %).

Utilization of whole cell mediated deracemization in a chemoenzymatic synthesis of enantiomerically enriched polycyclic chromeno[4,3-b] pyrrolidines.

Various aryl and alkyl substituted optically pure propargyl alcohols were obtained with excellent ee (up to >99%) and isolated yields (up to 87%) by deracemization using whole cells of Candida parapsilosis ATCC 7330. The whole cells show substrate specificity towards alkyl substituted propargyl alcohols and a switch in the enantioselectivity has been observed from 'R' to 'S' upon increasing the chain length. For the first time, enantiopure (R)-4-(3-hydroxybut-1-ynyl)benzonitrile, (R)-4-(biphenyl-4-yl)but-3-yn-2-ol, (S)-ethyl 3-hydroxy-5-phenylpent-4-ynoate and (S)-4-phenylbut-3-yne-1,2-diol were obtained using this strategy.

Disaggregation induced solvatochromic switch: a study of dansylated polyglycerol dendrons in binary solvent mixture.

A reversal in solvatochromic behaviour was observed in second and third generation glycerol based dansylated polyether dendrons in water on addition of a second solvent like methanol or acetonitrile. Below a certain percentage of the nonaqueous solvent there is a negative-solvatochromism observed and above that there is a switch to positive-solvatochromism. The negative-solvatochromism is attributed to the progressive disaggregation of the dendron aggregates by the nonaqueous solvent component.

Asymmetric reduction of alkyl-3-oxobutanoates by Candida parapsilosis ATCC 7330: insights into solvent and substrate optimisation of the biocatalytic reaction.

Asymmetric reduction of alkyl-3-oxobutanoates mediated by Candida parapsilosis ATCC 7330 resulted in optically pure alkyl-3-hydroxybutanoates in good yields (up to 72%) and excellent enantiomeric excess (up to >99 %). A detailed and systematic optimisation study was necessary and was carried out to avoid the undesired transesterification reaction during the course of asymmetric reduction. Under optimised conditions, the (S)-alkyl hydroxyesters were produced predominantly except for the methyl ester which formed the (R)-enantiomer.

Expression, purification, crystallization and preliminary X-ray diffraction analysis of carbonyl reductase from Candida parapsilosis ATCC 7330.

The NAD(P)H-dependent carbonyl reductase from Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoate to ethyl (R)-4-phenyl-2-hydroxybutanoate, a precursor of angiotensin-converting enzyme inhibitors such as Cilazapril and Benazepril. The carbonyl reductase was expressed in Escherichia coli and purified by GST-affinity and size-exclusion chromatography. Crystals were obtained by the hanging-drop vapour-diffusion method and diffracted to 1.

Asymmetric synthesis of (S)-ethyl-4-chloro-3-hydroxybutanoate using Candida parapsilosis ATCC 7330.

Asymmetric reduction of ethyl-4-chloro-3-oxobutanoate to (S)-ethyl-4-chloro-3-hydroxybutanoate in aqueous medium by resting cells of Candida parapsilosis ATCC 7330 was optimized. The influence of culture parameters (inoculum size, inoculum age and biocatalyst harvest time) and reaction parameters (co-substrate, resting cell, pH and substrate concentrations) on the asymmetric reduction were studied. It was found that these parameters significantly influenced the rate of the asymmetric reduction.

Comparison of a potentiometric and a micromechanical triglyceride biosensor.

Sensitive biosensors for detection of triglyceride concentration are important. In this paper we report on two types of silicon based triglyceride sensors: an electrolyte-insulator-semiconductor capacitor (EISCAP) which is a potentiometric device and a polysilicon microcantilever. The detection principle for both sensors is based on the enzymatic hydrolysis of triglyceride though the sensing mechanisms are different: electronic for the EISCAP and mechanical for the microcantilever.

Miniaturization of EISCAP sensor for triglyceride detection.

In this paper we discuss the fabrication and characterization of miniaturized triglyceride biosensors on crystalline silicon and porous silicon (PS) substrates. The sensors are miniaturized Electrolyte Insulator Semiconductor Capacitors (mini-EISCAPs), which primarily sense the pH variation of the electrolyte used. The lipase enzyme, which catalyses the hydrolysis of triglycerides, was immobilized on the sensor surface.