Momordica charantia seed proteins - Purification, biochemical characterization of a class II α-mannosidase isoenzyme and its interaction with the lectin and protein body membrane.

Momordica charantia seeds contain a galactose specific lectin and mixture of glycosidases. These bind to lectin-affigel at pH 5.0 and are all eluted at pH 8.0. From the mixture, α-mannosidase was separated by gel filtration (purified enzyme Mr âˆ¼ 238 kDa). In native PAGE (silver staining) it showed three bands that stained with methylumbelliferyl substrate (possible isoforms). Ion exchange chromatography separated two isoforms in 0.5 M eluates and one isoform in 1.0 M eluate. In SDS-PAGE it dissociated to Mr ∼70 and 45 kDa subunits, showing antigenic similarity to jack bean enzyme. MALDI analysis confirmed the 70 kDa band to be α-mannosidase with sequence identity to the genomic sequence of Momordica charantia enzyme (score 83, 29 % sequence coverage). The pH, temperature optima were 5.0 and 60o C respectively. Kinetic parameters KM and Vmax estimated with p-nitrophenyl α-mannopyranoside were 0.85 mM and 12.1 U/mg respectively. Swainsonine inhibits the enzyme activity (IC50 value was 50 nM). Secondary structural analysis at far UV (190-300 nm) showed 11.6 % α-helix and 36.5 % ß-sheets. 2.197 mg of the enzyme was found to interact with 3.75 mg of protein body membrane at pH 5.0 and not at pH 8.0 suggesting a pH dependent interaction.

Isolation of Momordica charantia seed lectin and glycosidases from the protein bodies: Lectin-glycosidase (ß-hexosaminidase) protein body membrane interaction reveals possible physiological function of the lectin.

Momordica charantia seeds are known to contain a galactose specific lectin that has been well characterized. Seed extracts also contain glycosidases such as the ß-hexosaminidase, α-mannosidase and α-galactosidase. In the present study, lectin was affinity purified from the seed extracts and protein bodies isolated by sucrose density gradient centrifugation. From the protein bodies, lectin was identified and ß-hexosaminidase was isolated by lectin affinity chromatography and subsequently separated from other glycosidases by gel filtration. In the native PAGE, the purified ß-hexosaminidase migrated as a single band with a molecular weight of ∼235 kDa and by zymogram analysis using 4-methylumbelliferyl N-acetyl-ß-D-glucosaminide substrate it was confirmed as ß-hexosaminidase. Under reducing conditions in SDS-PAGE, the purified enzyme dissociated into three bands (Mr 33, 20 and 15 kDa). The prominent bands (20 and 15 kDa) showed immunological cross-reactivity with the human Hexosaminidase B antibody in a western blot experiment. In gel digestion of the purified enzyme, followed by proteomic analysis using tandom MS/MS revealed sequence identity as compared to the genomic sequence of the Momordica charantia with a score of 57 (24% sequence coverage). Additionally, by CD analysis the purified ß-hexosaminidase showed 39.1% of α-helix. Furthermore, secondary structure variations were observed in presence of substrate, lectin and at different pH values. Protein body membrane prepared from the isolated protein bodies showed a pH dependent interaction with the purified lectin and mixture of glycosidases.

Nutraceutical inherent of Spinacia oleracea Linn. methanolic leaf extract ameliorates isoproterenol induced myocardial necrosis in male albino Wistar rats via mitigating inflammation.

Cardiovascular diseases (CVDs) remain the principal cause of death in both developed and developing countries. The present study was intended to appraise the nutraceutical inherent of HPLC standardized Spinacia oleracea methanolic leaf extract (SoLE) in isoproterenol (ISO) induced male albino Wistar rats via activation of pro-inflammatory signaling pathway that drives myocardial necrosis. Biochemical analysis of ISO injected rats showed significant alterations in the activities of homocysteine, paraoxonase, lecithin cholesterol acyltransferase, C-reactive protein, myeloperoxidase and caspase-3 which were further confirmed by the histopathological examination. In addition, it also flaunted a significant increase in pro-inflammatory cytokines, such as TNF-α, IL-1ß, IL-6 in ISO administered rats when compared with normal control rats. Pretreatment with SoLE (100, 200, and 300mg/kg bw) along with positive control gallic acid, significantly prevented all the adverse effects in ISO administered rats in a dose dependent manner. These results also reiterated the expected amelioration of myocardial necrosis in ISO induced MI rats conveying anti-atherogenic, anti-apoptotic and anti-inflammatory activities of SoLE.