Chapter 17

Amino Acid

Catabolism

Urea

Excretion

as

Conversion to:

pyruvate

acetyl-CoA

citric acid cycle intermediates

Digestion by

proteases

Digestion by

proteases

cytosol

mitochondria

NH4+

NH4+

Protein

Aminotransferases

catalyze transfer of

amino groups

of amino acids to

a-ketoglutarate

Predict the product

of amino acid catabolism

• Alanine ??

Aspartate ??

Glutamate ??

• Draw the structure of each amino acid and

then predict the product of the transamination

reaction. Hint: count the carbons.

Prentice Hall c2002 Chapter 16 9

NH3

Glucose-alanine cycle

Blood Urea Nitrogen (BUN)

• Blood urea nitrogen (BUN) measures the amount of urea nitrogen, a

waste product of protein metabolism, in the blood. BUN is commonly

monitored in hospitals and nursing homes.

• Adult BUN: 7-20 mg/100 ml; men may be slightly higher

• Predict whether BUN will increase or decrease in the following cases.

• Dehydrated patient? Overhydration?

• Elderly patient? Newborn?

• High protein diet? Malnutrition?

• Intestinal bleeding?

• Pregnancy?

• Kidney failure? Liver failure?

• Impaired nutrient absorption?