3-DIMENSIONAL MOLECULAR MODELING OF BOVINE CASEINS - A REFINED, ENERGY-MINIMIZED KAPPA-CASEIN STRUCTURE

A refined three-dimensional molecular model of kappa-casein has been p roduced using energy minimization techniques and a Kollman force field on a previously reported predicted three-dimensional structure. This initial model was constructed via molecular modeling techniques from s equence-based secondary structural prediction algorithms. Both the ini tial and refined structures agreed with global secondary structure ana lysis from vibration spectroscopy. The refined structure contained man y of the features of the initial model, including two sets of antipara llel beta-sheet structures containing predominantly hydrophobic side c hains, which could form interaction sites with alpha(s1)-casein. Two t ypes of energy-minimized dimer and tetramer models are presented: 1) u sing Cys as potential intermolecular disulfide binding sites and 2) us ing the two sheets as possible hydrophobic self-association sites, wit hout Cys interactions. All structures yielded good stabilization energ ies and are in agreement with chemical, biochemical, and physical chem ical results obtained for kappa-casein.