Principles of Biochemistry Volume 2 - A. Lehninger 1985

Bioenergetics and Metabolism
Oxidative Degradation of Amino Acids. The Urea Cycle
Some amino acids can be converted into glucose, while others are converted into ketone bodies.

We already know that Five Amino Acids degrade to ultimately yield acetoacetyl-CoA. In the Liver, these Amino acids can give rise to Ketone Bodies because acetoacetyl-CoA is capable of being converted into acetoacetate and ß-hydroxybutyrate (Section 18.10). The five amino acids in question are therefore termed ketogenic (Table 19-2). Their capacity to form ketone bodies becomes particularly pronounced in untreated Diabetes Mellitus; under these conditions, the liver produces large amounts of ketone bodies derived not only from Fatty acids but also from ketogenic amino acids.

Class="center">Table 19-2. Glucogenic and ketogenic amino acids

The fifteen amino acids that degrade to form $\alpha$-ketoglutarate, succinate, and oxaloacetate can be converted into glucose and Glycogen via the pathway described in Chapter 20. They are referred to as glucogenic amino acids (Table 19.2). There is no sharp boundary between ketogenic and glucogenic amino acids, as Two amino acids (Phenylalanine and Tyrosine) belong to both groups simultaneously. Certain amino acids that are converted into Pyruvate, notably alanine, cysteine, and serine, also have the potential to form acetoacetate via acetyl-CoA, particularly in patients with diabetes mellitus (Sections 18.10, 19.3).