Oligopeptidases are enzymes involved in the degradation of short peptides (generally less than 30 amino acids in size) which help pathogens evade the host defence mechanisms. Leptospira is a zoonotic pathogen and causes leptospirosis in mammals. Proteome analysis of Leptospira revealed the presence of oligopeptidase A (OpdA) among other membrane proteins. To study the role of oligopeptidase in leptospirosis, the OpdA of L. interrogans was cloned and expressed in Escherichia coli with a histidine tag (His-tag). The protein showed maximum expression at 37 °C with 0.5 mM of IPTG after 2 h of induction. Recombinant OpdA protein was purified to homogeneity using Ni-affinity chromatography. The purified OpdA showed more than 80% inhibition with a serine protease inhibitor but the activity was reduced to 30% with the cysteine protease inhibitor. The peptidase activity was increased significantly in the presence of Zn at a neutral pH. Inhibitor assay indicate the presence of more than one active sites for peptidase activity as reported with the OpdA of E. coli and Salmonella. Over-expression of OpdA in E. coli BL21 (DE3) did not cause any negative effects on normal cell growth and viability. The role of OpdA as virulence factor in Leptospira and its potential as a therapeutic and diagnostic target in leptospirosis is yet to be identified.

Objective: The present investigation aimed to assess the nutritional, mineral profiling and anti-nutritional analysis of Gynochthodes umbellata (Syn. Morinda umbellata), an underutilized edible plant belongs to the family Rubiaceae. Literature perusal reveals that, there are no previous reports on nutritional studies for this valuable fruit. Methods: Nutritional, mineral profiling and anti-nutritional analysis of fruits were carried out. Results: In nutritional analysis, carbohydrates (6.98 g/100g fw), protein (2.68 g/100 g fw), crude fat (0.13 mg/g dw) and crude fibre (32.58%) content were detected. The fruits of G. umbellata, Vitamin C (25 mg/100g fw) was higher when compared to other three vitamin evaluated, Four macro elements and 6 micro elements were also quantified. Conclusion: Nutritional and Anti-nutritional analysis reveals that, the G. umbellata fruits could be used as a source of protein, vitamin and minerals and highly recommended for consumption as they contain low amount of the anti-nutrients analysed. This is the first report on nutritional analysis of G. umbellata fruit.

Heterologous expression of Integral Membrane Proteins (IMPs) is reported to be toxic to the host system in many studies. Even though there are reports on various concerns like transformation efficiency, growth properties, protein toxicity, inefficient expression and protein degradation in IMP overexpression, no studies so far addressed these issues in a comprehensive way. In the present study, two transmembrane proteins of the pathogen Leptospira interrogans , namely Signal peptidase (SP), and Leptospira Endostatin like A (Len-A) were taken along with a cytosolic protein Hydrolase (HYD) to assess the differences in transformation efficiency, protein toxicity, and protein stability when over expressed in Escherichia coli ( E. coli ). Bioinformatics analysis to predict the transmembrane localization indicated that both SP and Len are targeted to the membrane. The three proteins were expressed in full length in the E. coli expression strain, BL 21 (DE3). Significant changes were observed for the strains transformed with IMP genes under the parameters analysed such as, the transformation efficiency, survival of colonies on IPTG-plate, culture growth kinetics and protein expression compared to the strain harbouring the cytosolic protein gene.

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