Aspartate amino transferase (AST) is another enzyme widely used in clinics to assess the severity of liver disorders and myocardial infarction. It is used to detect relapsing hepatic cirrhosis. To produce a candidate reference material for this enzyme the experimental approach will be through genetic engineering and molecular biology techniques. Previous knowledge of the molecular structure and activity of gamma-glutamyltransferase would be a template for the preparation of AST. Subsequent steps will follow the same pattern as for the other enzyme preparations.
The first step, the feasibility study on gamma-glutamyltransferase (GGT) used as a model, was completed in 1989. The expression of GGT cDNA in E. Coli and yeast appeared to be possible. Cell culture using the HepG2 hepatoma cell line was successful and could yield a GGT material whose kinetic and immunological properties were shown to be close to those of human serum GGT. The results are presented in report EUR 12842 (1990). The application to AST should follow after completion of the project no 294 on ALT.