ABSTRACT
Flavonoids are recognized to regulate animals' food digestion processes trough interaction with digestive enzymes. The binding capacity of hesperetin (HES), luteolin (LUT), quercetin (QUE), catechin (CAT) and rutin (RUT) with pancreatic α-amylase were evaluated, using UV-Vis spectroscopy, fluorescence and molecular docking. Using p-nitrophenyl-α-d-maltopentoside (pNPG5) as substrate analog, LUT showed the best inhibitory capacity, even better than that of the positive control, acarbose (ACA). A mixed-type inhibition was observed for HES, LUT and QUE, a competitive-type for ACA, while no inhibition was observed with CAT and RUT. In agreement with kinetic results, α-amylase presented a higher affinity for LUT, when analyzed by fluorescence quenching. The binding of flavonoids to amylase followed a static mechanism, where the binding of one flavonoid per enzyme molecule was observed. Docking analysis showed that flavonoids bound near to enzyme active site, while ACA bound in another site behind the catalytic triad. Extrinsic fluorescence analysis, together with docking analysis pointed out that hydrophobic interactions regulated the flavonoid-α-amylase interactions. The present study provides evidence to understand the relationship of flavonoids structure with their inhibition mechanism.
Subject(s)
Flavonoids/chemistry , Flavonoids/pharmacology , alpha-Amylases/antagonists & inhibitors , alpha-Amylases/chemistry , Binding Sites , Flavonoids/metabolism , Humans , Molecular Docking Simulation , Protein Binding , Structure-Activity Relationship , alpha-Amylases/metabolismABSTRACT
AIM: To select carbazole-degrading bacteria able to survive and metabolize carbazole in biphasic organic-water media and to study the factors affecting carbazole degradation in such conditions. METHODS AND RESULTS: In this research a new carbazole-degrading strain was isolated from hot springs in Mexico. This bacterium was preliminary identified as Burkholderia sp. IMP5GC and was able to grow using carbazole as sole carbon and nitrogen source. Genetic analysis showed that this bacterium carries carA genes identical to those reported in Pseudomonas resinovorans CA10. Burkholderia IMP5GC efficiently degraded carbazole in aqueous media as well as in biphasic media with n-hexadecane. Furthermore, the strain IMPGC5 efficiently reduced the concentration of carbazole and monomethyl carbazole species in gas oil-water biphasic media. CONCLUSIONS: This study demonstrates the biodegradation of carbazole in biphasic gas oil/water media (1 : 1), regardless of the highly toxic effects of this petroleum distillate. SIGNIFICANCE AND IMPACT OF THE STUDY: Biodegradation of carbazole in biphasic media contributes to the understanding and design of bioprocesses for carbazole removal from petroleum-upgrading fractions and other carbazole-rich organic mixtures.
Subject(s)
Burkholderia/metabolism , Carbazoles/metabolism , Carcinogens, Environmental/metabolism , Alkanes/metabolism , Biodegradation, Environmental , Burkholderia/drug effects , Burkholderia/genetics , Carbazoles/pharmacology , Carbon-Nitrogen Ligases/genetics , Carcinogens, Environmental/pharmacology , Culture Media , Gasoline , Genes, Bacterial/genetics , Petroleum , Temperature , Water MicrobiologyABSTRACT
Glucosamine-6P-deaminase (EC 3.5.99.6, formerly glucosamine-6-phosphate isomerase, EC 5.3.1.10) from Escherichia coli is an attractive experimental model for the study of allosteric transitions because it is both kinetically and structurally well-known, and follows rapid equilibrium random kinetics, so that the kinetic K(m) values are true thermodynamic equilibrium constants. The enzyme is a typical allosteric K-system activated by N-acetylglucosamine 6-P and displays an allosteric behavior that can be well described by the Monod-Wyman-Changeux model. This thermodynamic study based on the temperature dependence of allosteric parameters derived from this model shows that substrate binding and allosteric transition are both entropy-driven processes in E. coli GlcN6P deaminase. The analysis of this result in the light of the crystallographic structure of the enzyme implicates the active-site lid as the structural motif that could contribute significantly to this entropic component of the allosteric transition because of the remarkable change in its crystallographic B factors.
Subject(s)
Acetylglucosamine/analogs & derivatives , Aldose-Ketose Isomerases/chemistry , Entropy , Escherichia coli/enzymology , Acetylglucosamine/metabolism , Aldose-Ketose Isomerases/metabolism , Allosteric Regulation/physiology , Binding Sites/physiology , Models, Chemical , Protein Binding/physiology , Protein Conformation , Structure-Activity Relationship , Substrate Specificity/physiology , Temperature , ThermodynamicsABSTRACT
Taurine is an amino acid known to possess trophic properties in the central nervous system. The relevance of its presence in maternal milk is related to its role as an essential nutrient. Taurine deficiency around birth produces anatomical and functional modifications in the brain and in the retina. In addition, taurine favors neuron proliferation and survival, as well as neurite extension. The mechanisms by which taurine exerts its trophic role in the regenerating retina are related to increases in calcium fluxes, to modifications of protein phosphorylation, and to influence of the target organ. Moreover, taurine-zinc interaction might be crucial in the development of structures such as the hippocampal formation. Thus, taurine can be considered as one of the determinant nutritional molecules during development and regeneration of the central nervous system.
