Harness molecular modeling to predict activity, functionality.

Scientists like yourself have long relied on using models, developed from theoretical knowledge, to study and predict how chemical and biological systems behave on the molecular level. In recent years, pharmaceutical researchers have used computer-aided molecular modeling to alter molecular structures or design new molecules that eventually lead to new drugs.

USDA/ARS investigators (Eastern Regional Research Center, 600 E. Mermaid La., Wyndmoor, PA 19118) are applying molecular modeling to food science. They are attempting to tailor functionality on the molecular level by modeling such proteins as casein, as well as nucleic acids, peptides and polysaccharides. The technology will have significant ramifications across the board. Areas of interest have included flavor and sweetener development, fat substitutes and texture improvement.

ARS scientists applied molecular modeling to gain a better understanding of how casein functions in mozzarella cheese. This enabled them to develop a low-fat mozzarella cheese that melts in much the same way that a full-fat mozzarella melts. Eventually, it might be possible to develop a better fat replacer by modeling, then redesigning, structure on the molecular level.

There are a number of commercially available molecular modeling software packages targeted at the pharmaceutical market that could help food scientists and product designers. Many sophisticated systems are able to visualize molecules in three dimensions. In addition, you might be able to rotate images in real time, as well as visualize other structural aspects, including solvent-accessible surfaces or van der Waals radii. Current systems enable you to create and update models rapidly, and predict certain properties without having to go as far as synthesizing molecules.

The objective is to study structure-function relationships and to predict activity or functionality on the molecular level. This data could eventually be applied to develop new products or improve current ones. For example, scientists could model proteins to create more stable ones or others that have characteristics tailored for a specific application. An example of this involves work on the caseins, in which molecular models were built to better understand the functionality of these milk proteins. The caseins are complexed with calcium and phosphorous into small packages called micelles. When rennet, cheese and yogurt cultures, and calcium are added to milk during yogurt- and cheesemaking, changes occur on the surfaces of the micelles that cause the milk to change from a liquid to a semisolid.

To gain a better understanding of the first steps in this process, scientists extended their computer model of the surface of the casein complex to study how this is changed by the addition of calcium. They learned that calcium can bind to the milk protein's surface in a quite unexpected way that may affect the normal structure of the complex. This data will aid cheese and yogurt manufacturers who are attempting to streamline their procedures and enhance the nutritional qualities of their products.

Further information. Harry Farrell; phone: [phone]; fax: [phone].