This project involves studies on the chemical structure, molecular conformation, and physicochemical characteristics of certain natural biopolymeric materials and their synthetic analogs with the aim of relating the resulting structural information to their biological model of action. Current emphasis is focused on proteins that play a role in cell growth regulation, cell transformation or differentiation. Emphasis is placed on applying the modern spectroscopic methodologies of mass spectrometry, nuclear magnetic resonance and circular dichroism, as well as the standard methods of protein sequencing, to the solution of these problems. Projects include: 1) Structural studies on gamma-glutamyl transpeptidase (GGT), a tumor marker enzyme of unknown structure. A rapid HPLC method was developed to preparatively separate the enzyme into its subunits. Two dimensional gel electrophoresis on the active enzyme demonstrated 7 isozymic components in the 24,000 molecular weight range and at least 11 isozymic components in the 52,000 molecular weight range. All electrophoretically separated components were found to be immunoreactive to anti-GGT antibodies. N-Terminal amino acid sequencing was accomplished on the light and heavy subunits to the extent of 36 and 32 residues, respectively. The resulting data allows for further work in the area of gene cloning studies and also in comparison of the enzyme found in various biological matrices. 2) Fast atom bombardment mass spectrometry. Spectral measurements on standard peptides indicates that the method is applicable for obtaining valuable accurate molecular weight information on peptides in the several thousand mass range, complementing but not displacing the results obtainable by classical sequencing techniques. Group specific derivatization by brominated reagents were found to improve our predictive ability to sequence peptides. These methods are also being applied to blocked peptides, such as N-terminal pyroglutamates, where classical sequencing techniques are not effective.
