Deamination and transamination
The amino acid threonine has its amino group removed by threonine dehydratase (1p209). This particular amino acid is commonly deaminated along with glutamate, histidine, serine and glycine (1p209). In the case of thronine, the reaction proceeds with loss of water, which is why the enzyme catalyzing the reaction is called a dehydratase instead of a deaminase (1p209). Vitamin B6 is important for this reaction to occur (1p209). The amino group is used by periportal hepatocytes to synthesize urea (1p209).
The transfer of an amino groupf from one amino acid to an amino acid carbon skeleton or alpha-keto acid occurs to feed protein synthesis (1p209). The enzymes include tyrosine aminotransferase, branched-chain aminotransferases, alanine aminotransferase, and aspartate aminotransferase (1p209). The enzymes can often require vitamin B6 in a coenzyme form (1p209). The reactions are reversible and are often used to create non-essential amino acids from essential ones except lysine, histidiene and threonine (1p209).
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.