Twelve strains of Bacillus licheniformis isolated from traditionally fermented African locust bean (Parkia biglobosa) were evaluated in respect to production of protease on skim milk agar. B. licheniformis LBBL-11 exhibited the highest proteolytic activity with an average area of clear zone measuring 960 mm 2 . Production of protease from B. licheniformis LBBL-11 was further studied by growing the strain on nutrient broth. Maximum protease production was 18.4 U/mL at 48 h of growth, which coincided with the end of exponential phase. The protease from this Bacillus sp. had optimum pH of 8.0 and was stable over a wide pH range of 5.0-11.0. The optimum temperature for the protease activity was 60C. The enzyme was 95% stable at 60C after 60 min of incubation. These properties indicate possible application of B. licheniformis LBBL-11 as potential starter culture for the fermentation of African locust bean under controlled conditions of temperature and pH.
PRACTICAL APPLICATIONSAfrican locust bean seeds (Parkia biglobosa) are rich in protein and usually fermented to a tasty food condiment (iru) used as flavor intensifier for soups. This is highly consumed in developing and under developed countries
The non-enzymatic and enzymatic antioxidant defense systems play a major role in detoxification of pro-oxidant endobiotics and xenobiotics. The possible involvement of beetle non-enzymatic [α-tocopherol, glutathione (GSH), and ascorbic acid] and enzymatic [catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), and polyphenol oxidase (PPO)] antioxidant defense system on the insecticidal activity of synthetic insecticides (cypermethrin, 2,2-dicholorovinyl dimethyl phosphate, and λ-cyhalothrin) and ethanolic plant extracts of Tithonia diversifolia, Cyperus rotundus, Hyptis suaveolens leaves, and Jatropha Curcas seeds was investigated. 2,2-Dicholorovinyl dimethyl phosphate (DDVP; 200 ppm, LC 50 = 13.24 ppm) and T. diversifolia (20,000 ppm) resulted in 100% beetle mortality at 96-hour post-treatment. The post-treatments significantly increased the beetle α-tocopherol and GSH contents. Activities of CAT, SOD, POX, and PPO were modulated by the synthetic insecticides and bioinsecticides to diminish the adverse effect of the chemical stresses. Quantitative and qualitative allelochemical compositions of bioinsecticides and chemical structure of synthetic insecticides possibly account and for modulation of their respective enzyme activities. Altogether, oxidative stress was enormous enough to cause maladaptation in insects. This study established that oxidative imbalance created could be the molecular basis of the efficacy of both insecticides and bio-insecticides. Two, there was development of functional but inadequate antioxidant defense mechanism in the beetle.
Protein carbamylation is of great concern both in vivo and in vitro. Here, we report the first structural characterization of a protein carbamylated at the N-terminal proline. The unexpected carbamylation of the R-amino group of the least reactive codified amino acid has been detected in high-resolution electron density maps of a new crystal form of the HIV-1 protease/saquinavir complex. The carbamyl group is found coplanar to the proline ring with a trans conformation. The reaction of N-terminal with cyanate ion derived from the chaotropic agent urea was confirmed by mass spectra analysis on protease single crystals. Implications of carbamylation process in vitro and in vivo are discussed.KEYWORDS Carbamylation, N-terminal proline, HIV-1 protease/saquinavir complex, single crystals T he HIV protease (PR) is an aspartic protease that shares sequence homology around the active site with other retroviral proteases, as the conserved Asp-ThrGly catalytic triad. 1 PR is required for proteolytic cleavage of viral Gag and Gag-Pol polyproteins into individual structural and functional proteins during viral maturation. 2 In the absence of this proteolysis, immature noninfectious virions are produced, thus making PR a prime target for structureassisted drug design in antiviral therapy. 3,4 The structure-assisted drug design and discovery process utilizes techniques such as protein crystallography, nuclear magnetic resonance (NMR), and computational biochemistry to guide synthesis of potential drugs. PR has been widely characterized biochemically and structurally, which has led to the discovery of HIV protease inhibitors (PIs). Their utilization in highly active antiretroviral therapy (HAART) has been a major turning point in the management of HIV/acquired immune-deficiency syndrome (AIDS). 5 Recently, we have demonstrated that high-resolution X-ray crystallography can be used as a powerful method to identify the most potent PR inhibitor present in an epimeric mixture. 6 The pseudosymmetric peptidomimetic inhibitor based on a novel Phe-Pro isostere core matched the 2-fold symmetry of the homodimeric structure of the PR. Fourier maps obtained by high-resolution diffraction data (1.3 Å) clearly showed the catalytic site fully occupied by a single ordered stereoisomer. On the contrary, several X-ray crystal structures of PR complexed with more asymmetric FDAapproved inhibitors, like darunavir, nelfinavir, and saquinavir (SQV), have the catalytic site occupied by the inhibitor oriented in two almost equivalent positions related by a pseudo-2-fold symmetry. [7][8][9][10][11][12] To investigate this order/disorder phenomenon and its possible relationship with crystal packing, we have undertaken a systematic search for new crystal forms of wild-type PR in complex with SQV. Single crystals of the PR/SQV complex were obtained by a vapor diffusion technique and analyzed by X-ray diffraction. These crystals belong to a new monoclinic crystal form, which contains two dimers of the complex in the asymmetric unit. Other crystal...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.