6 research outputs found
New Therapeutic Strategies to Lower Blood Stream Cholesterol Levels through the Inhibition of HMG-CoA Reductase
An atomic-level perspective of HMG-CoA-reductase: The target enzyme to treat hypercholesterolemia
UIDB/04378/2020 PTDC/QUI-QFI/31689/2017This review provides an updated atomic-level perspective regarding the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), linking the more recent data on this enzyme with a structure/function interpretation. This enzyme catalyzes one of the most important steps in cholesterol biosynthesis and is regarded as one of the most important drug targets in the treatment of hypercholesterolemia. Taking this into consideration, we review in the present article several aspects of this enzyme, including its structure and biochemistry, its catalytic mechanism and different reported and proposed approaches for inhibiting this enzyme, including the commercially available statins or the possibility of using dimerization inhibitors.publishersversionpublishe
Toward the Mechanistic Understanding of Enzymatic CO2 Reduction
SFRH/BD/116515/2014
PTDC/BBB-EBB/2723/2014
UID/Multi/04378/2019
grant agreement number 810856Reducing CO2 is a challenging chemical transformation that biology solves easily, with high efficiency and specificity. In particular, formate dehydrogenases are of great interest since they reduce CO2 to formate, a valuable chemical fuel and hydrogen storage compound. The metal-dependent formate dehydrogenases of prokaryotes can show high activity for CO2 reduction. Here, we report an expression system to produce recombinant W/Sec-FdhAB from Desulfovibrio vulgaris Hildenborough fully loaded with cofactors, its catalytic characterization and crystal structures in oxidized and reduced states. The enzyme has very high activity for CO2 reduction and displays remarkable oxygen stability. The crystal structure of the formate-reduced enzyme shows Sec still coordinating the tungsten, supporting a mechanism of stable metal coordination during catalysis. Comparison of the oxidized and reduced structures shows significant changes close to the active site. The DvFdhAB is an excellent model for studying catalytic CO2 reduction and probing the mechanism of this conversion.publishersversionpublishe
Ontogenetic changes in digestive enzyme activity and biochemical indices of larval and postlarval European lobster (<i>Homarus gammarus, L</i>)
Unraveling the Enigmatic Mechanism of l‑Asparaginase II with QM/QM Calculations
In
this paper, we have studied the catalytic mechanism of l-asparaginase
II computationally. The reaction mechanism was investigated
using the ONIOM methodology. For the geometry optimization we used
the B3LYP/6-31G(d):AM1 level of theory, and for the single points
we used the M06-2X/6-311++G(2d,2p):M06-2X/6-31G(d) level of theory.
It was demonstrated that the full mechanism involves three sequential
steps and requires the nucleophilic attack of a water molecule on
the substrate prior to the release of ammonia. There are three rate-limiting
states, which are the reactants, the first transition state, and the
last transition state. The energetic span is 20.2 kcal/mol, which
is consistent with the experimental value of 16 kcal/mol. The full
reaction is almost thermoneutral. The proposed catalytic mechanism
involves two catalytic triads that play different roles in the reaction.
The first triad, Thr12-Lys162-Asp90, acts by deprotonating a water
molecule that subsequently binds to the substrate. The second triad,
Thr12-Ty25-Glu283, acts by stabilizing the tetrahedral intermediate
that is formed after the nucleophilic attack of the water molecule
to the substrate. We have shown that a well-known Thr12-substrate
covalent intermediate is not formed in the wild-type mechanism, even
though our results suggest that its formation is expected in the Thr89Val
mutant. These results have provided a new understanding of the catalytic
mechanism of l-asparaginases that is in agreement with the
available experimental data, even though it is different from all
earlier proposals. This is of particular importance since this enzyme
is currently used as a chemotherapeutic drug against several types
of cancer and in the food industry to control the levels of acrylamide
in food
Global metabolite profiling reveals transformation pathways and novel metabolomic responses in Solea senegalensis after exposure to a non-ionic surfactant
Alcohol polyethoxylate (AEO) surfactants are widely used in household and industrial products, but the health effects arising from short-term exposure to sublethal concentrations are unknown. A metabolomic approach was used to investigate the biotransformation and effects of exposure to sublethal concentrations of hexaethylene glycol monododecylether (C12EO6) in juvenile sole, Solea senegalensis. After 5 days, C12EO6 was rapidly metabolized in the sole by oxidation, glucuronidation, and ethoxylate chain shortening. C12EO6 exposure at either 146 or 553 mu g L-1 resulted in significant metabolite disruption in liver and blood samples, including an apparent fold increase of >10(6) in the circulating levels of C-24 bile acids and C-27 bile alcohols, disturbance of glucocorticoid and lipid metabolism, and a 470-fold decrease in levels of the fatty acid transport molecule palmitoyl carnitine. Depuration resulted in rapid elimination of the surfactant and normalization of metabolites toward pre-exposure levels. Our findings show for the first time the ability of metabolomic analyses to discern effects of this AEO on metabolite homeostasis at exposure levels below its no effect concentrations for survival and reproduction in juvenile fish. The pronounced alteration in levels of liver metabolites, phospholipids, and glucocorticoids in S. senegalensis in response to surfactant exposure may indicate that this contaminant could potentially impact a number of health end points in fish