X-ray diffraction analysis of the inhibition of porcine pancreatic elastase by a peptidyl trifluoromethylketone

X-ray crystallographic data to 2.57 A resolution (1 A = 0.1 nm) have been measured for the complex of a peptidyl trifluoromethylketone inhibitor with porcine pancreatic elastase (PPE); R = 0.14. The inhibitor forms a stable complex with the enzyme by means of a covalent attachment to active site Ser195O gamma, resulting in a hemiketal moiety with tetrahedral geometry. The tripeptide protion binds as an antiparallel beta-sheet, with four hydrogen bonds augmenting the active-site covalent linkage, Ki = 9.5 microM. His57 exhibits a bifurcated H-bond to both Ser195O gamma and an F atom of the inhibitor. This study is one of a series which explores the binding geometry of a variety of small substrates and inhibitors to PPE. This peptidyl-PPE complex affords insight into the binding geometry of a novel trifluoromethylketone moiety to a serine proteinase.     

Inactivation of the transcription factor <Emphasis Type="Italic">mig1</Emphasis> (<Emphasis Type="Italic">YGL035C</Emphasis>) in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> improves tolerance towards monocarboxylic weak acids: acetic,formic and levulinic acid

Toxic concentrations of monocarboxylic weak acids present in lignocellulosic hydrolyzates affect cell integrity and fermentative performance of Saccharomyces cerevisiae. In this work, we report the deletion of the general catabolite repressor Mig1p as a strategy to improve the tolerance of S. cerevisiae towards inhibitory concentrations of acetic, formic or levulinic acid. In contrast with the wt yeast, where the growth and ethanol production were ceased in presence of acetic acid 5 g/L or formic acid 1.75 g/L (initial pH not adjusted), the m9 strain (Δmig1::kan) produced 4.06?±?0.14 and 3.87?±?0.06 g/L of ethanol, respectively. Also, m9 strain tolerated a higher concentration of 12.5 g/L acetic acid (initial pH adjusted to 4.5) without affecting its fermentative performance. Moreover, m9 strain produced 33% less acetic acid and 50–70% less glycerol in presence of weak acids, and consumed acetate and formate as carbon sources under aerobic conditions. Our results show that the deletion of Mig1p provides a single gene deletion target for improving the acid tolerance of yeast strains significantly.     

Evaluation of antioxidant and anticancer activities of chemical constituents of the Saururus chinensis root extracts

Evaluation of antioxidant and anticancer activities were screened by various Saururus chinensis root extracts. Four solvents (ethyl acetate, methanol, ethanol, and water) extracts were investigated for their total flavonoids, phenol contents and their antioxidant activity of DPPH (2,2-diphenyl-1-picrylhydrazyl), NO (nitric oxide), H₂O₂ (hydrogen peroxide), ABTS 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid)diammonium assays, FRAP (ferric reducing ability of plasma) assays and anticancer activity. The total phenolic and flavonoid content of extracts were determined by using FC (Folin–Ciocalteu) and AlCl₃ colorimetric assay method. Total flavonoid content in these plants ranged from 24.7 to 72.1 mg g^?1 and amount of free phenolic compounds was between 11.2 and 67.1 mg g^?1 extract. The all extracts have significant levels of phenolics and flavonoids content. Anticancer activity was screened for MCF-7 breast cancer cell line. Ethanol extract shows significant of antioxidant activity and water extract shows significant of anticancer activity compared with standard (BHT) butylated hydroxy toluene. These ethanol and water extracts could be considered as a natural source for using antioxidant, and anticancer agents compared to commercial available synthetic drugs.     

Multivalent Binding of a Ligand-Coated Particle: Role of Shape,Size, and Ligand Heterogeneity

We utilize a multiscale modeling framework to study the effect of shape, size, and ligand composition on the efficacy of binding of a ligand-coated particle to a substrate functionalized with the target receptors. First, we show how molecular dynamics along with steered molecular dynamics calculations can be used to accurately parameterize the molecular-binding free energy and the effective spring constant for a receptor-ligand pair. We demonstrate this for two ligands that bind to the ${\alpha }_5{\beta }_1$-domain of integrin. Next, we show how these effective potentials can be used to build computational models at the meso- and continuum-scales. These models incorporate the molecular nature of the receptor-ligand interactions and yet provide an inexpensive route to study the multivalent interaction of receptors and ligands through the construction of Bell potentials customized to the molecular identities. We quantify the binding efficacy of the ligand-coated-particle in terms of its multivalency, binding free-energy landscape, and the losses in the configurational entropies. We show that 1) the binding avidity for particle sizes less than 350 nm is set by the competition between the enthalpic and entropic contributions, whereas that for sizes above 350 nm is dominated by the enthalpy of binding; 2) anisotropic particles display higher levels of multivalent binding compared to those of spherical particles; and 3) variations in ligand composition can alter binding avidity without altering the average multivalency. The methods and results presented here have wide applications in the rational design of functionalized carriers and also in understanding cell adhesion.     

Dietary Supplement of Medicinal Herbal Leaf Powder on Growth Performance,Digestive Enzymes Activities,Energy Utilization and Vitamin Levels of the Freshwater Prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis>

Experiments were conducted to evaluate the influence of dietary supplement (@ 5%) dried leaf powder of the medicinal herbs, Ocimum sanctum, Solanum trilobatum and Phyllanthus amarus on survival, growth, activities of digestive enzymes, energy utilization, and vitamin contents of the freshwater prawn, Macrobrachium rosenbergii. Results indicated significant (P < 0.05) improvements in survival, growth, activities of digestive enzymes, energy utilization, and vitamin levels in herb supplemented feeds fed prawns group compared to prawns fed non-herbs feed. Best growth was noted in prawns fed with the feed supplemented by leaf powder of P. amarus, followed by S. trilobatum and O. sanctum. It is concluded that leaf powder of these herbs can be used as dietary supplement for better growth of freshwater prawn.     

Accumulation of Heavy Metals in Some Marine Fisheries Resources Collected from Gulf of Mannar Marine Biosphere Reserve,Southeast Coast of India

Concentrations of toxic metals viz. mercury (Hg), cadmium (Cd) and lead (Pb) were evaluated in four species of fishes (Sardinella longiceps, Selaroides leptolepis, Epinephelus quoyanus and Lethrinus lentjan), one species of shrimp (Penaeus semisulcatus) and one species of crab (Portunus sanguinolentus) sampled from Thoothukudi, Keelakarai and Veerapandian pattinam of Gulf of Mannar, Southeast coast of India. Results revealed accumulation of these metals in the following order Hg > Cd > Pb. Hg concentration was found to be higher in Po. sanguinolentus followed by E. quoyanus, Pe. semisulcatus and L. lentjan however, the same was absent in Sa. longiceps and Se. leptolepis. Cd concentration was recorded in decreasing order in Po. sanguinolentus > Pe. semisulcatus > L. lentjen > E. quoyanus > Sa. longiceps > Se. leptolepis. Pb was detectable only in four species. Results of One-way ANOVA revealed significant variations (p < 0.05) in accumulation of Cd in Sa. longiceps, Se. leptolepis and Pe. semisulcatus and Hg in E. quoyanus, L. lentjan and Po. sanguinolentus. Variations noted in Pb were not statistically significant throughout.     

Studies on bound trans-4-hydroxy-l-proline in sandal (Santalum album L.)

1. trans-4-Hydroxy-l-proline was found to occur in the bound state in the leaves of sandal (Santalum album L.), in which large amounts of free cis-4-hydroxy-l-proline are also present. 2. Bound trans-4-hydroxy-l-proline was present, associated mainly with a `wall' fraction and a `soluble' fraction roughly in equal proportions. 3. Bound proline is present only in small amounts in the `soluble' fraction but is mostly associated with the `wall' fraction and the other sedimented fractions. 4. In the free amino acid fraction more than 98% of the hydroxyproline had the cis-configuration, whereas in the `wall' and `soluble' fractions more than 90% of the bound hydroxyproline was in the trans-configuration. 5. Various extraction procedures indicated heterogeneity of the hydroxyproline-containing components. Hot 5% (w/v) trichloroacetic acid extracts about 25% of hydroxyproline and m-NaOH extracts an additional 25%. 6. Incorporation of [¹⁴C]proline into the bound hydroxyproline was demonstrated. The hydroxyproline component of the `soluble' fraction does not appear to be the precursor of that of the `wall' fraction.     

Crystal structures of the complex of porcine pancreatic elastase with two valine-derived benzoxazinone inhibitors

The crystal structures of porcine pancreatic elastase complexed to two similar benzoxazinone inhibitors are reported to 2.09 A and 1.76 A resolution, and refined to conventional R factors of 0.153 and 0.172.