Biochimica fisica

Linee di Ricerca

Biomembranes, lipid peroxidation and antioxidants

There are large classes of molecules of biological interest, which include drugs like anaesthetics, narcotics and antidepressants, as well as cytotoxic molecules, whose effects can be related to an aspecific interaction with the lipid phase of the biomembranes. It is well known, in fact, that, in
biomembranes, a largely cooperative behaviour between proteins and their surroundings exists and that the protein specific membrane functions can be affected by agents that do not bind specifically to proteins, but, interacting with lipids, alter the bilayer structure.

Mono and multilamellar liposomes of different phospholipid compositions, are a widely adopted model
for these studies, as they reproduce many of the physical chemical properties of biomembranes, like fluidity, permeability to ions, hydrophobic barrier, surface charge distribution. In our laboratory the modifications, induced by dopants, on the lipid organisation of the bilayer are investigated by differential scanning calorimetry (DSC) and electron spin resonance (ESR) techniques.

In this context we study also the antioxidant properties of some natural molecules present in food which carry out a protecting action towards the cell against damages produced by the oxygen and its reactive species (ROS).

The research in this field is articulated in the following subjects:

• comparison of the different methods of measurement of the antioxidant capacity of a molecule and verification of the variability of the results;
• measure of the antioxidant properties of food, natural extracts and purified molecules (natural of synthetic) with particular attention to their capacity of inhibition of the lipid peroxidation;
• correlation between antioxidant properties and chemical structure, and study of the chemical mechanism correlated to the antioxidant property.

Enzymes, structure and function

Amine oxidases are ubiquitary enzymes which catalyze the oxidative deamination of biogenic amines with production of ammonia, hydrogen peroxide and of the corresponding aldehydes. In particular, amine oxidases purified by animal plasma regulate the concentrations of the polyamines, linear compounds of hydrocarbon structure intercalate by more amine groups, at least one of which in terminal position. Polyamines are characterized by a high density of positive charge at physiological pH which makes them to interact electrostatic ally with  molecules or macromolecules of particular physiological importance, such as the phosphate ion and the a-helix of the DNA, modifying their chemical physical and structural properties.

In this field the research group is working to study the structure of the active site and the catalytic mechanism of amine oxidases from different sources (vegetables and animals) through kinetic measurements carried out at different experimental conditions, using substrates of precise chemical
structure.                   
 

Immobilized enzymes

Due to their high catalytic efficiency and extraordinary specificity, the enzymes are used in the clinical and chemical analysis and more recently also in the synthesis of organic and pharmaceutical compounds. In fact, the soft operative conditions of  action of the enzymes, i.e. pH, temperature,
solvent, etc., make possible the synthesis or the modification of precise functional groups of organic compounds of particular complexity, such as drugs or natural compounds, that are not possible or very difficult applying the traditional methods of the organic chemistry.

In this field, the group is undertook to research new applications of the enzymes in the analytical and clinical chemistry  and for the synthesis of organic compounds also studying the possibility of the immobilization of the enzymes to inert solid matrix, in order to assemble microbioreactors  and
biosensors with analytical and synthesis aims.  

In particular our group is adjusting new biosensors designed for the analytical determination of parameters.