Kanti Nandan Mihooliya

The marine environment is known for its vast diversity of the microbial population; however, less explored for bioactive compounds. In this study, an AMP produced by a new marine isolate, Vibrio proteolyticus MT110, showed broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria. The AMP was purified to homogeneity using ethyl acetate extraction followed by RP-HPLC, and LC-MS analysis showed its molecular weight as 980 Da. The MIC of AMP (peptide-MT110) was obtained in the 7.81-31.25 µg/mL range against different indicator strains. Peptide-MT110 showed stability of its antimicrobial activity at 15-121 °C and pH 4-10 and in the presence of various hydrolytic enzymes. The peaks at 1536 cm^-1 and 1712 cm^-1 wavenumbers in FTIR spectra confirmed the peptidic nature of AMP, and its amino acid analysis confirmed the presence of tyrosine and isoleucine. The antibacterial activity of peptide-MT110 is confirmed by PI assay and TEM. The optimization of peptide-MT110 production using statistical methods resulted in a 2.64-fold higher production. The physicochemical properties and stability in wide pH and temperature ranges showed the potential of peptide-MT110 for its development as a drug candidate. This is believed to be the first report on an AMP from Vibrio proteolyticus.

The present study reports the structural and functional characterization of a new glutaminase-free recombinant L-asparaginase (PrASNase) from Pseudomonas resinovorans IGS-131. PrASNase showed substrate specificity to L-asparagine, and its kinetic parameters, K _m , V _max , and k _cat were 9.49×10 ^-3 M, 25.13 IUmL ^-1 min ^-1 , and 3.01×10 ³ s ^-1 , respectively. The CD spectra showed that PrASNase consists of 30.9% α-helix and 69.1% other structures in its native form. FTIR was used for the functional characterization, and molecular docking predicted that the substrate interacts with serine, alanine, and glutamine in the binding pocket of PrASNase. Different from known asparaginases, structural characterization by small-angle X-ray scattering (SAXS) and analytical ultracentrifugation (AUC) unambiguously revealed PrASNase to exist as a monomer in solution at low temperatures and oligomerized to a higher state with temperature rise. Through SAXS studies and enzyme assay, PrASNase was found to be mostly monomer and catalytically active at 37°C. Furthermore, this glutaminase-free PrASNase showed killing effects against WIL2-S and TF-1.28 cells with IC ₅₀ of 7.4 µg.mL ^-1 and 5.6 µg.mL ^-1 , respectively. This is probably the first report with significant findings of fully active L-asparaginase in monomeric form using SAXS and AUC and demonstrates the potential of PrASNase in inhibiting cancerous cells, making it a potential therapeutic candidate. HIGHLIGHTS: A new L-asparaginase (PrASNase) was structurally and functionally characterized. SAXS revealed PrASNase is functionally active in monomeric form and oligomerizes with temperature rise. Monomeric PrASNase showed an IC ₅₀ value of 7.4 and 5.6 µg mL ^-1 against WIL2-S and TF-1.28 cells. Cytotoxicity of PrASNase against leukemic cell lines showed its potential as a biotherapeutic. GRAPHICAL

Background: L‐Asparaginase is an essential enzyme for the food and biopharmaceutical industry. The stability, however, of L‐asparaginase is widely known to be an issue. Commercial manufacturing of any biopharmaceutical involves hold‐ups during processing, and can result in product loss if stability is an issue, as is the case with L‐asparaginase. This interplay of product intermediate stability and process design is the focus of this investigation.Methods and Results: In this study, we propose a strategy to simultaneously increase the refolding yield and stability of refolded L‐asparaginase so as to improve overall process yield. Using one variable at a time (OVAT) experiments, urea (6 M), solubilized inclusion bodies (15 mg/ml), refolding method (step dilution), and pH (8.6) were identified as significant process parameters. A design of experiment (DOE)‐based optimization was then performed for the refolding step. The net outcome was more than a three‐fold increase in enzyme recovery (i.e., 4.90 IU/ml) compared to unoptimized conditions (i.e., 1.26 IU/ml). Further, the L‐asparaginase process intermediate was found to be stable for more than a week at room temperature and 2–8°C, while the unoptimized sample was stable at 2–8°C but did not show any activity at room temperature after 72 h.Conclusions: The current study elucidates how process intermediate stability needs to be given due consideration during process optimization, particularly for products such as L‐asparaginase which are labile.