• Non ci sono risultati.

TABACCHI, GLORIAVANONI M. A.GAMBA, ALDOFOIS, ETTORE SILVESTROmostra contributor esterni nascondi contributor esterni 

N/A
N/A
Protected

Academic year: 2021

Condividi "TABACCHI, GLORIAVANONI M. A.GAMBA, ALDOFOIS, ETTORE SILVESTROmostra contributor esterni nascondi contributor esterni "

Copied!
1
0
0

Testo completo

(1)

Flavocytochrome b

2

(Fcb2) is a flavin-dependent redox enzyme that catalyzes the oxidation of L-lactate to pyruvate. The mechanism of this enzymatic reaction, in particular the lactate C H bond cleavage step, is still debated.

Relevant physicochemical properties of L -lactate, a substrate of Fcb2, have been calculated both in the vacuum and in an active-site model of the enzyme.

The results indicate that negative hyperconjugation effects in L -lactate are a key factor for the determination of the Fcb2-catalyzed L -lactate-to-pyruvate dehydrogenation mechanism. Indeed, these effects, responsible for the C H bond weakening in the isolated L-lactate molecule, are enhanced when L-lactate hydroxyl group is involved in a hydrogen bond with the active site base of the Fcb2 enzyme in the Michaelis complex.

Negative hyperconjugation effects (also known as Bolhmann effects or n- * interactions), which are also present in the substrates of other flavin-dependent enzymes, may be of general relevance in understanding the mechanism of dehydrogenation reactions catalyzed by flavoenzymes.

The picture shows the negative hyperconjugation interaction between the lone pair on the oxygen atom

and the antibonding orbital *(C H ) of the L-lactate molecule.

Riferimenti

Documenti correlati

We focus on the characterization of the orbitals in the excited state wave functions, on the electronic density evolution from the united atom to dissociation, on

Motivation for this work comes not only from obtaining potential energy curves for the high excited states of H 2 but also from characterizing the electronic density evolution from

We propose a simple classical dynamical model of a thermoelectric sor thermochemicald heat engine based on a pair of ideal gas containers connected by two unequal scattering

It works in real time and provides instantaneous two-dimensional velocity mappings in the direction orthogonal to the optical axis, independently of the particle concentration and

Given the ease with which the appropriate deterministic benchmarks can be generated, and the fact that the convergence of parallel tempering on these systems has been measured

In metadynamics runs performed at other pres- sures and temperatures, we observed several reconstructive transitions to phases that are topologically different both from

Rock varnish, erosional grooves, and well-developed cavernous weathering phenomena occur in close association on a small biotite-monzogranite nunatak in the Northern Foothills

Polymeric carbon nitride, whic h is c heap, amenable to mass preparation and c hemic al modific ation, and highly stable against oxidation up to 550 °C in air, has been exemplified