Ezequiel Leiva

Computer simulations topics
  protein-nanoparticle hybrid systems.

Biomacromolecules (BM), such as proteins (enzymes, antibodies, etc),
DNA, or carbohydrates, have dimensions on the nanometer scale, and are
therefore comparable to the size of the metal and semiconductor
nanoparticles (NP). This similarity in size facilitates the construction
of hybrid systems which combine the electronic, magnetic and optical
properties of NP, with the fine specificity of recognition, catalysis,
energy transduction and cooperativity of the BM. With such a combination
it would be possible to add new photonic properties to a protein, or use
the recognition properties of an antibody to direct the location of the
NP to a given type of cell of an organism, to name a few posibilities.
Moreover, these hybrid systems NP-BM may have new properties that are
not in their original components separately and may give rise to new
functions or materials.

Our current efforts are mainly focused in two related problems

-Structural and dynamic characterization of the ligands coating metal
The ligan layer that cover and passivate metal NP is of fundamental
importance in the formation of the NP-BM hybrids, since this layer is
the main mediator in the interaction. The physicochemical
characteristics of this layer and the solvent that comes in contact with
it, can be used to select which proteins are going to interact and which
not, as well as can cause changes in the structure and behavior of a BM.

-Stability of secondary the structure of peptides bound to a NP model.
To understand how the secondary structure of a protein is affected by
the interaction with the NP, we are using model peptides. We are studing
the interaction of the peptide AK16, which has a high content of
alpha-helix in solution, and a peptide derived from chignolina whose
secondary structure is mainly a hairpin. With this model systems we try
to anticipate the behavior of alpha-helices and beta sheets of proteins.