Review Beta Oxidation

Protein Metabolism

20 aa’s that combine in unique arrangements to form individual proteins

Amino Acids  Amino radical (NH 2 )  Carboxyl group (COOH)  The side chain (carbon, hydrogen, sometimes sulfur or nitrogen) is what gives it specific characteristics  10 aa’s are essential, cannot be synthesized in the body

All aa’s become part of the amino acid pool: three compartments  blood  liver  skeletal muscle

aa’s in the compartments are in equilibrium; change one, change all, blood is the communicator  if one compartment is low, can replenish from another: glucose-alanine cycle

aa’s brought to liver, converted to glucose (gluconeogenesis) and released in blood for delivery to working muscle

aa’s in muscle are converted to alanine, carried to liver, where amino radical is removed (deamination) carbon skeleton is converted to glucose

After 4 hours of continuous exercise, liver’s output of alanine-derived glucose accounts for 45% of total hepatic glucose

As intensity of exercise increases; so does alanine release from exercising muscles (7X)

Energy derived from glucose- alanine cycle can account for 10-15% of the total energy requirement

Amino acid metabolism can be divided as  disposal of the alpha-amino group (via alpha-ketogluterate to glutamate to ammonia to urea)  carbon skeletons are converted to intermediates of metabolism

If energy state is high: convert to acetyl-CoA and stored as fat

If energy state is low: catabolized to support demand (exercise) for energy

Alanine, via pyruvate, yields 15 ATP