Sea Cucumber Intestinal Peptide Induces the Apoptosis of MCF-7 Cells by Inhibiting PI3K/AKT Pathway.

Sea cucumbers are one of many marine echinoderm animals that contain valuable nutrients and medicinal compounds. The bioactive substances in sea cucumbers make them have promising biological and pharmacological properties, including antioxidant, anti-bacterial, and anti-tumor effects. In this study, sea cucumber intestinal peptide (SCIP) is a small molecular oligopeptide (<1,000 Da) extracted from sea cucumber intestines hydrolyzed by alkaline protease. The analysis of amino acid composition showed that hydrophobic amino acids and branched-chain amino acids were rich in SCIP. Nowadays, although increasing studies have revealed the biological functions of the sea cucumber active substances, there are few studies on the function of SCIP. Furthermore, due to the anti-cancer activity being an essential characteristic of sea cucumber active substances, we also investigated the anti-cancer potential and the underlying mechanism of SCIP in vivo and in vitro. The results indicate that SCIP inhibits the growth of MCF-7 tumor cells in zebrafish and increases the apoptosis of human breast cancer MCF-7 cells. Further mechanism studies confirm that SCIP promotes the expression of apoptosis-related proteins and thus promotes the breast cancer cells (MCF-7) apoptosis via inhibition of PI3K/AKT signal transduction pathway.

Cloning, expression, characterization and homology modeling of a novel water-forming NADH oxidase from Streptococcus mutans ATCC 25175.

A novel nicotinamide adenine dinucleotide (NADH) oxidase from Streptococcus mutans ATCC 25175 (SmNox) was cloned and overexpressed in Escherichia coli BL21 (DE3). Sequence analysis revealed an open reading frame of 1374bp, capable of encoding a polypeptide of 457 amino acid residues. The molecular mass of the purified SmNox was estimated to be ∼49.9kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified SmNox had the highest specific activity of 281.2U·mg-1 at optimal pH and temperature of 7.0 and 35°C, with a Km of 57.7µM and a Vmax of 154.3U·mg-1. The good stability at room temperature was observed. Homology modeling and substrate docking were performed to evaluate the catalytic characteristics. The results indicated that Nicotinamide ring of NADH extends vertically toward to re-face of coenzyme (FAD), and the specific conformation of NADH suggested that the charges transfer in SmNox complex could be easier than in its homologous enzyme (LbNox) under alkaline environment. The characterization of the SmNox indicated it has potential in industrial regeneration of coenzyme NAD+ for coupling with dehydrogenases.

Preparation of Expoxy-Functionalized Magnetic Nanoparticles for Immobilization of Glycerol Dehydrogenase.

Immobilization of glycerol dehydrogenase (GDH) from Serratia marcescens H30 onto epoxy functional magnetic nanoparticles by covalent attachment was carried out. The optimal immobilization conditions were obtained as follows: enzyme/support 6.08 mg/g, temperature 25 °C, pH 7.0 and time 8 h. Under these conditions, a high immobilization yield above 90% was obtained. The characterization of the immobilized GDH indicated that enhanced pH and thermal stability were achieved. Kinetic parameters Km of free and immobilized GDH were determined as 10.35 mM and 15.76 mM, respectively. The immobilized GDH retained about 85% initial activity after ten cycles. These results suggested that GDH immobilized onto magnetic nanoparticles is a simple and efficient way for preparation of stable enzyme. And the immobilized GDH has potential applications in the production of DHA.

Immobilization of dehydrogenase onto epoxy-functionalized nanoparticles for synthesis of (R)-mandelic acid.

Epoxy functionalized magnetic Fe3O4@SiO2 nanoparticles were successfully prepared and characterized by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The prepared nanoparticles were used for immobilization of alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae by covalent attachment. The optimal immobilization conditions were obtained as follows: enzyme/support 4.49mg/g, pH 8.0, buffer concentration 0.05M, time 12h and temperature 30°C. Under these conditions, a high immobilization yield and efficiency of above 92% were obtained after the optimization. Broad pH tolerance and high thermostability were achieved by the immobilization. The immobilized ADH retained about 84% initial activity after five cycles. Kinetic parameters Vmax and Km of free and immobilized ADH were determined as 56.72µM/min, 44.27µM/min and 11.54mM, 31.32mM, respectively. (R)-mandelic acid synthesis with the immobilized ADH was carried out, and the yield of (R)-mandelic acid was as high as 64%. These results indicate that the ADH immobilized onto epoxy-functionalized nanoparticles is an efficient and simple way for preparation of stable ADH, and the immobilized ADH has potential applications in the production of (R)-mandelic acid.