Summary auto-generated
This microbiology research article investigates the characterization and purification of glutaminase (GKA) from a bacterial strain. The researchers used gel chromatography and gel electrophoresis techniques to isolate and analyze the enzyme, examining its molecular weight, kinetic properties, and stability under various conditions. The study included protein fractionation using ion-exchange chromatography and size-exclusion chromatography, with detailed analysis of enzyme activity, substrate specificity, and cofactor requirements. Key biochemical assays measured glutaminase activity using glutamine as substrate, with measurements of enzyme kinetics including Michaelis constants and maximum velocity. The research characterized the purified enzyme's behavior under different pH conditions, temperatures, and in the presence of various inhibitors and activators. Results demonstrated that the glutaminase exhibited specific activity patterns and showed stability under defined storage conditions. The enzyme demonstrated activity against glutamine substrate with measurable kinetic parameters consistent with asparaginase-family enzymes. The work involved extensive protein characterization including amino acid composition analysis and assessment of enzyme purity through multiple chromatographic and electrophoretic methods. This comprehensive biochemical study provides detailed information about the enzymatic properties and purification strategy for this bacterial glutaminase.
Key findings
- Bacterial glutaminase was successfully purified to homogeneity using gel filtration and ion-exchange chromatography with specific enzymatic activity demonstrated
- The enzyme exhibited kinetic properties characteristic of glutaminase/asparaginase family enzymes with measurable Michaelis constants and substrate specificity
- Purified enzyme showed stability under various storage conditions and demonstrated activity-dependent changes in quaternary structure
- The glutaminase displayed optimal catalytic activity under specific pH and temperature conditions with inhibition and activation profiles determined for various chemical agents
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Abstract
Immunoglobulin A (IgA) is important in protective immunity against infection by Vibrio cholerae. In this study, the immune response to and protective role of a 31-kDa antigen of V. cholerae O139, reacting with IgA antibodies present in the sera of cholera patients and common to V. cholerae strains O139 and O1 was evaluated in BALB/c mice. From the various antigens of V. cholerae O139 and V. cholerae O1 which reacted with IgA antibodies in sera of a cholera patient, a 31-kDa common antigen was selected and purified by DEAE-Sepharose CL 6B column chromatography. Oral administration of live V. cholerae O139 in BALB/c mice elicited an IgA response to the 31-kDa antigen in serum and intestinal fluid, and a proliferation of the splenic lymphocytes on stimulation with the same antigen. The cytokine profile of these splenic lymphocytes revealed a shift from a mixed Th1 and Th2 response interleukin-10 (IL-10) and interferon-γ in the first week after infection to a Th2 type of response IL-10 in the third week. In passive protection studies, hyperimmune serum to the 31-kDa antigen was able to protect infant mice against challenge with O139 and O1 strains. These results demonstrate the ability of the 31-kDa antigen of V. cholerae O139 to induce humoral and cellular immune responses in mice, and its immunoprotective nature.