Nadir Naveed Siddiqui

Structural analysis and characterization of dextran produced by wild and mutant strains of Leuconostoc mesenteroides.

An exopolysaccharide known as dextran was produced by Leuconostoc mesenteroides KIBGE-IB22 (wild) and L. mesenteroides KIBGE-IB22M20 (mutant). The structure was characterized using FTIR, (1)H NMR, (13)C NMR and 2D NMR spectroscopic techniques, whereas surface morphology was analyzed using SEM. A clear difference in the spectral chemical shift patterns was observed in both samples. All the spectral data indicated that the exopolysaccharide produced by KIBGE-IB22 is a mixture of two biopolymers. One was dextran in α-(1 → 6) configuration with a small proportion of α-(1 → 3) branching and the other was levan containing β-(2 → 6) fructan fructofuranosyl linkages. However, remarkably the mutant only produced dextran without any concomitant production of levan. Study suggested that the property of KIBGE-IB22M20, regarding improved production of high molecular weight dextran in a shorter period of fermentation time without any contamination of other exopolysaccharide, could be employed to make the downstream process more feasible and cost effective on large scale.

Mutational analysis and characterization of dextran synthesizing enzyme from wild and mutant strain of Leuconostoc mesenteroides

Dextransucrase producing Leuconostoc mesenteroides KIBGE IB-22 was subjected to mutagenesis by exposing the strain to UV irradiation. The dextransucrase produced by both the strains (wild and mutant) were characterized and the catalytic properties of both wild and mutant dextransucrase were compared. Among 42 mutants, KIBGE IB-22M20 exhibited 6.75 times increase in dextransucrase activity as compared to the wild one. Wild dextransucrase showed specific activity of 31.3 DSU/mg of protein with V(max) and K(m) of 18.84 DSU/ml/h and 77.09 mM, respectively at 30 °C in 0.3 M citrate buffer (pH 4.5) using sucrose as substrate. Whereas, mutant dextransucrase exhibited a specific activity of 173.2 DSU/mg with V(max) and K(m) values of 104.2DSU/ml/h and 101.7 mM, respectively at 35 °C in 0.3 M citrate buffer (pH 5.0) keeping the same substrate as for wild. Dextransucrase from both wild and mutant showed an approximate molecular weight of 221 kDa by SDS-PAGE.

DNA methyltransferase 1, 3a, and 3b expression in hepatitis C associated human hepatocellular carcinoma and their clinicopathological association

Identification of biomarker will obligate a substantial influence on various cancer management and treatment. We hypothesize that genetic/proteomic and epigenetic studies should be uncovering modifications which may be independently or jointly affect the expression of the genes that are involved in the progression of liver cancer (LC). For this purpose, we examined the effect of expressional changes of DNMTs on HCV infected LC of different genotypes. We found that both mRNA and protein expression levels of DNMT1, 3a, and 3b were upregulated in genotype 1b and 3a HCV infected patients as compared to control. However, DNMT3b mRNA levels did not change in genotypes 2a, 3, and 4, but were upregulated at the protein level by genotype 1b, 2a, and 3a. Furthermore, no significant changes were observed for DNMTs investigated in sample expressing the genotypes 5 and 6. Our findings suggest that HCV at least in part by altering DNMTs expression may play a significant role in HCC progression.

Bioprospecting of indigenous resources for the exploration of exopolysaccharide producing lactic acid bacteria

Exploration of biodiversity lead towards the discovery of novel exopolysaccharide (EPS) producing microbes that have multiple applications. The safety compatibility status of lactic acid bacteria (LAB) makes it an attractive candidate for the production of EPS in industries. Therefore, new bacterial isolates are continuously being identified from different habitats. Current research was conducted to explore indigenous biodiversity for the production of dextransucrase, which is involved in the synthesis of dextran. Dextran is an EPS which is used in different industries. In this study, thirty-nine LAB were isolated from different food samples. The isolates were identified as genus Leuconostoc, Weissella and Streptococcus based on genotypic and phenotypic characteristics. Screening revealed that only eight isolates can produce dextransucrase in high titres. Fermentation conditions of dextran producing LAB was optimized. The results indicated that Weissella confusa exhibited maximum specific activity (1.50 DSU mg−1) in 8 h at 25 °C with pH 7.5. Dextran produced from Weissella proved to be a useful alternative to commercially used dextran produced by Leuconostoc mesenteroides in industries for various applications.

Influence of Metal ions, Surfactants and Organic Solvents on the Catalytic Performance of Levansucrase from Zymomonas mobilis KIBGE-IB14

A significant progress has been made in discovering and developing new bacterial polysaccharides producing enzymes possessing extremely functional properties. Levan is a natural polymer of fructose linked by β (2→6) glycosidic bond which is produced by transfructosylation reaction in the presence of levansucrase. Among wide range of microorganisms, Zymomonas mobilis is considered as the most promising candidate for the production of extracellular levansucrase. It has potential applications in multiple industries from pharmaceutics, cosmetics to food industries. Determination of levansucrase characteristics is necessary to increase its industrial applications. This concept has directed much interest towards enzyme characterization by observing its effects against different chemicals. The present investigation focused on the characterization of levansucrase by observing its behavior with reference to different metal ions, surfactants and organic solvents. The results showed that these chemicals acted as activators, inhibitors or stabilizers. In metal ions, different activators (K + , Na + , Cs + , Ba +2 , Ca +2 , Cu +2 , Mg +2 and Mn +2 ) and inhibitors (Co +2 , Hg +2 , Fe +3 and Al +3 ) were investigated. Among them, Hg +2 found to be strong inhibitor as it inhibits enzyme activity by 92% at 1 mM. Non-ionic surfactants i.e. triton X-100, tween-20 and tween-80 considered as stabilizers while anionic surfactant such as sodium dodecyl sulphate (SDS) inhibited the enzyme activity by 11%. Moreover, ethanol and methanol stabilized the enzyme activity while other solvents observed as inhibitors or stimulators.

Introducing differential expression of human heat shock protein 27 in hepatocellular carcinoma: moving toward identification of cancer biomarker

Previously, it has to be acknowledged that overexpressed heat shock protein B27 (HSPB27) have been implicated in the etiology of wide range of human cancers. However, the molecular mechanism leading to the disease initiation to progression in liver cancer is still unknown. Present work was undertaken to investigate the differentially expressed HSPB27 in association with those damages that lead to liver cancer development. For the identification of liver cancer biomarker, samples were subjected to comparative proteomic analysis using two-dimensional gel electrophoresis (2-DE) and were further validated by Western blot and immunohistochemical analysis. After validation, in silico studies were applied to demonstrate the significantly induced phosphorylated and S-nitrosylated signals. The later included the interacting partner of HSPB27, i.e., mitogen-activated protein kinase-3 and 5 (MAPK3 and 5), ubiquitin C (UBC), v-akt murine thymoma viral oncogene homolog 1 (AKT1), mitogen-activated protein kinase 14 (MAPK14), and tumor protein p53 (TP53), which bestowed with critical capabilities, namely, apoptosis, cell cycling, stress activation, tumor suppression, cell survival, angiogenesis, proliferation, and stress resistance. Taking together, these results shed new light on the potential biomarker HSPB27 that overexpression of HSPB27 did lead to upregulation of their interacting partner that together demonstrate their possible role as a novel tumor progressive agent for the treatment of metastasis in liver cancer. HSPB27 is a promising diagnostic marker for liver cancer although further large-scale studies are required. Also, molecular profiling may help pave the road to the discovery of new therapies.