1. Worked Example 27.1 Predicting Transamination Products
The blood-serum concentration of the heart-muscle transaminase, aspartate aminotransferase (AST), is used in the diagnosis of heart disease because the enzyme escapes into the serum from damaged heart cells. AST catalyzes transamination of aspartate with -ketoglutarate. What are the products of this reaction?
Analysis
The reaction is the interchange of an amino group from aspartate with the keto group from -ketoglutarate. We know that -ketoglutarate always gives glutamate in transamination, so one product is glutamate. The product from the amino acid will have a keto group instead of the amino group; we need to consider various amino acid structures to identify a candidate.
Consulting Table 18.3 (which lists the structures of the 20 amino acids), we see that the structure of aspartate (aspartic acid) is
Removing the —NH3+ and —H groups bonded to the  carbon and replacing them by a O gives the desired
-keto acid, which in this case happens to be oxaloacetate.

2. Worked Example 27.1 Predicting Transamination Products
Continued
Solution
The overall reaction is therefore