Antibody and Protein Engineering Group

Structural basis of antibody affinity maturation
The project focuses on the study of antibody affinity maturation in the system of the phenyl-oxazolone. When conjugated to a carrier and injected into mice, in fact, the 2-phenyl-oxazolone induces the appearance of at least three different classes of antibodies ( I, II , III), each of which is formed by a different combination of light and heavy chains (L and H). Inside each class, the antibodies are characterized by increasing affinity and by an incremental number of point mutations. In particular, the main change that occurs during maturation of Class I and II, and that leads to increased stability of the bond between antibody and antigen, is a reduction of the speed of separation of the antigen (denoted by koff). It is not clear, however the reason for the existence of two different types of antibodies (Classes I and II) that undergo the same type of maturation achieving the same level of affinity. To clarify this point, the project aims to study the changes in the molecular structure of antibodies during their maturation in the experimental system of 2 -phenyl- oxazolone. Ten antibodies were then chosen representative of affinity maturation in each class. In this way, we intend to clarify which factors are influenced by the structural changes involved in antigen-antibody binding.

L-asparaginase of Helicobacter pylor
This line of research concerns a factor involved in the pathogenesis of Helicobacter pylori, which has developed from observations of the Sommi et al. ( 2002) on the inhibition of cell cycle induced by the broth culture filtrate of different strains of Helicobacter pylori. This led to the isolation of the factor responsible for inhibition of the cell cycle, L -asparaginase. The subsequent biochemical characterization of the enzyme, carried out in collaboration with Prof. Giovanna Valentini, has enabled us to deduce that its properties are potentially interesting from the point of view of biotechnological applications in various fields, from which the filing of an international patent (PCT / EP No. 2008/ 006 469 , Annex 1).

At the time, the study of site-directed and random mutants in order to isolate interesting variants of the enzyme is in due course.