T.B. Sridharan

Bio: T.B. Sridharan is an academic researcher from VIT University. The author has contributed to research in topics: Semen & Sperm. The author has an hindex of 9, co-authored 33 publications receiving 187 citations. Previous affiliations of T.B. Sridharan include Defence Research and Development Establishment.

Investigation on pH/salt-responsive multifunctional itaconic acid based polymeric biocompatible, antimicrobial and biodegradable hydrogels

Abstract: The present investigation focused on a new kind of pH-tunable IAD polymeric hydrogels based on itaconic acid (IA), acrylic acid (AA) and diethylene glycol (DEG), were synthesized by free radical polymerization viz. organic solventless approach and they were characterized by FT-IR, SEM analysis. For successive biocompatible hydrogels, biological activities were mainly considered for investigation. The swelling studies showed that the IAD hydrogels exhibited significantly greater pH-responsive swelling in alkaline medium and achieved up to 2200%. The salt responsive behaviour of IAD hydrogels proved that the results of swelling equilibrium decreased with increasing charge of the cation. Since, the prepared hydrogels were anionic in nature, excellent antibacterial zone of inhibition achieved towards gram + ve pathogens. It was found that the IAD hydrogels were performed better antifungal zone of inhibition against C. albicans. The IAD hydrogels pronounced noticeable zone of inhibition towards various pathogens even for pristine (without antibiotic) samples. The prepared itaconic acid based hydrogels were nontoxic due to their IC-50% values. The IAD hydrogels underwent for biodegradation due to n-number of ester moieties. It facilitated, hydrolysis of polymeric skeleton and achieved 88% of degradation. It was found that IA based pH-sensitive polymeric hydrogels were nontoxic with aggregable biomedical properties.

Screening, production, optimization and characterization of β-glucosidase using microbes from shellfish waste.

Abstract: An extracellular β-glucosidase was isolated from Proteus mirabilis VIT117 found to be growing on prawn shells. The enzyme production was found to be enhanced (14.58 U/ml) when the culture was maintained at pH 9 and provided with sorbitol as carbon source, yeast extract as nitrogen source and incubated at 37 °C for approximately 72 h. Statistical methods like Plackett-Burman and RSM were also applied here to study the effects of different combinations of growth parameters for the bacteria, where the most significant parameters were found to be inoculum size, pH, yeast extract, incubation time and sorbitol. The optimum concentrations of inoculum size, pH and yeast extract determined by RSM were 2 %, 9 and 2 %, respectively. Partial purification of the protein was done by ammonium sulfate precipitation, followed by dialysis, gel filtration chromatography and SDS-PAGE. The enzyme was found to have a molecular weight of approximately 50 kDa and was observed to be most active at 37 °C in pH 9, with a sharp decline in the enzyme activity when temperature or the pH was increased. Enzyme kinetics study was performed to understand the catalytic behavior of the enzyme and it was found that our β-glucosidase had 5.613 U/ml and 0.082 mM as V max and K m values, respectively.

Mammalian caspases: structure ,a ctivation ,s ubstrates, and functions during apoptosis

Abstract: ■ Abstract Apoptosis is a genetically programmed, morphologically distinct form of cell death that can be triggered by a variety of physiological and pathological stimuli. Studies performed over the past 10 years have demonstrated that proteases play critical roles in initiation and execution of this process. The caspases, a family of cysteine-dependent aspartate-directed proteases, are prominent among the death proteases. Caspases are synthesized as relatively inactive zymogens that become activated by scaffold-mediated transactivation or by cleavage via upstream proteases in an intracellular cascade. Regulation of caspase activation and activity occurs at several different levels: ( a) Zymogen gene transcription is regulated; ( b) antiapoptotic members of the Bcl-2 family and other cellular polypeptides block proximity-induced activation of certain procaspases; and ( c) certain cellular inhibitor of apoptosis proteins (cIAPs) can bind to and inhibit active caspases. Once activated, caspases cleave a variety of intracellular polypeptides, including major structural elements of the cytoplasm and nucleus, components of the DNA repair machinery, and a number of protein kinases. Collectively, these scissions disrupt survival pathways and disassemble important architectural components of the cell, contributing to the stereotypic morphological and biochemical changes that characterize apoptotic cell death.