No abstract

No abstract

BACKGROUND: Plant mediated synthesis of metallic nanoparticles has been studied and reported, however, to date, the biomolecules involved in the synthesis of metallic nanoparticles have not been characterized. This study was therefore undertaken to characterize the biomolecules of Syzygium cumini involved in the synthesis of silver nanoparticles.

No abstract

BackgroundElucidation of molecular mechanism of silver nanoparticles (SNPs) biosynthesis is important to control its size, shape and monodispersity. The evaluation of molecular mechanism of biosynthesis of SNPs is of prime importance for the commercialization and methodology development for controlling the shape and size (uniform distribution) of SNPs. The unicellular algae Chlamydomonas reinhardtii was exploited as a model system to elucidate the role of cellular proteins in SNPs biosynthesis.ResultsThe C. reinhardtii cell free extract (in vitro) and in vivo cells mediated synthesis of silver nanoparticles reveals SNPs of size range 5 ± 1 to 15 ± 2 nm and 5 ± 1 to 35 ± 5 nm respectively. In vivo biosynthesized SNPs were localized in the peripheral cytoplasm and at one side of flagella root, the site of pathway of ATP transport and its synthesis related enzymes. This provides an evidence for the involvement of oxidoreductive proteins in biosynthesis and stabilization of SNPs. Alteration in size distribution and decrease of synthesis rate of SNPs in protein-depleted fractions confirmed the involvement of cellular proteins in SNPs biosynthesis. Spectroscopic and SDS-PAGE analysis indicate the association of various proteins on C. reinhardtii mediated in vivo and in vitro biosynthesized SNPs. We have identified various cellular proteins associated with biosynthesized (in vivo and in vitro) SNPs by using MALDI-MS-MS, like ATP synthase, superoxide dismutase, carbonic anhydrase, ferredoxin-NADP+ reductase, histone etc. However, these proteins were not associated on the incubation of pre-synthesized silver nanoparticles in vitro.ConclusionPresent study provides the indication of involvement of molecular machinery and various cellular proteins in the biosynthesis of silver nanoparticles. In this report, the study is mainly focused towards understanding the role of diverse cellular protein in the synthesis and capping of silver nanoparticles using C. reinhardtii as a model system.

No abstract

No abstract

A novel protease is purified to homogeneity from the latex of a medicinally important plant Cryptolepis buchanani of family Apocynaceae (formerly Asclepiadaceae). The enzyme named cryptolepain has a molecular mass of 50.5 kDa. The isoelectric point and extinction coefficient (epsilon280nm1%) are 6.0 and 26.4, respectively. Cryptolepain contains 15 tryptophans, 41 tyrosines, and eight cysteine residues forming four disulfide bridges. The detectable carbohydrate moiety in the enzyme was found to be 6-7%. Cryptolepain hydrolyzes denatured natural substrates like casein, azocasein, and azoalbumin with high specific activity. The protease is exclusively inhibited by serine protease inhibitors phenylmethansulfonyl fluoride and diisopropyl fluorophosphate. Hydrolysis of azoalbumin by the cryptolepain is optimal in the pH range of 8-10 and temperatures of 65-75 degrees C. The enzyme shows high stability against pH (2.5-11.5), temperature (up to 80 degrees C), and chemical denaturants. The Km value of the enzyme was found to be 10 microM with azocasein as the substrate. The N-terminal sequence of cryptolepain is unique and shows only little homology to other known serine proteases, which makes this enzyme an ideal candidate for our ongoing biochemical and structure-function investigations of proteases. Easy availability of the latex and simple purification procedures make the enzyme a good system for exploring the biophysical chemistry of serine proteases as well as applications in the food industry.