Chapter 17 (part 2)

Protein Turnover and Amino Acid Catabolism

Dietary Protein Turnover

Protein Turnover Rates Vary

Ubiquitin Related Protein Degradation

Protein Ubiquitination

Multiple Ubiquitins can be polymerized to each other.

What determines whether a protein will become

ubiquinated?

Ubiquitinated Proteins are Degraded by the 26S

Proteosome

26S Proteosome

Removal of nitrogen

transaminase deaminase

Mechanisms to get rid of Ammonia

H2N

CH2N

O

HN

NH

NH

HN

O

OO

Urea Uric Acid

Urea Cycle

Urea Cycle

H2N

CH2N

O

Step 1: Formation of Carbamoyl Phosphate

Step 2: Ornithine Transcarbamyolase

Step 3: Argininosuccinate

Synthetase

Step 4: Argininosuccinase

• Cytosolic enzyme

Step 5: Arginase

Urea Cycle

Glucose-Alanine Cycle

Catabolism of Carbon Chains From Amino

Acids