Molecular Modeling in Studying of Protein Structure Alteration During the Process of Extrusion


Damir Kovaceka, Antonela Nincevica, Ivana Miljevica,Drazen Vikic-Topicb, Mladen Brncica, Branko Tripaloa, Damir Jezeka, Duska Curica, Damir Karlovica


a   Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia

b  Rudjer Boskovic Institute, POB 180, HR-1002 Zagreb, Croatia



During the process of extrusion biopolimers are exposed to high pressure and temperature. Chemical changes take places during process of gelatination, liquefaction and partial hydrolysis of biopolimers. Protein structure is altered during the extrusion, but mechanism of protein recombination is still not completely understood.

It is known that successive thermic treatments during the process of extrusion, give rise to formations isopeptide covalent bonds.

One approach to follow these changes in protein structure and formation of isopeptide cross-linking is FTIR spectroscopy combined with methods of molecular modeling based on ab initio and semiempirical quantum mechanical calculations.

In this research we were using semiempirical AM1 and ab initio HF/6-31G* calculation methods which help us to understand relationships among composition, structure and function in the sense of increasing quality and stability of final food products.