Amino Acid Oxidation & Urea Cycle

1. Background
2. Dietary
   1. Digestion
      1. gastrin
         1. pepsinogen
            1. pepsin
      2. food in SI
         1. secretin
         2. cholecystokinin (CKK)
            1. trypsinogen
            • trypsin
            1. chymotrypsinogen
            • chymotrypsin
         3. intestinal wall cells
            1. carboxypeptidases A & B
            2. aminopeptidases
   2. Acute pancreatitis
3. Amino Acid Oxidation Liver
   1. Step 1
      1. aminotranferases
         1. pyridoxal phosphate
   2. Step 2
      1. oxidative deamination
      1. glutamate dehydrogenase
4. Protein breakdown
   1. Transport forms
      1. glutamine synthetase
      2. Glucose-alanine cycle
         1. alanine aminotransferase
5. Ammonia badUrea cycle
   1. Excretory strategies
      1. Ammonotelic
      2. Ureotelic
      3. Uricotelic
   2. Pre-step
      1. carbamoyl phosphate
         1. carbamoyl phosphate synthase I (CPS I)
   3. Urea cycle
      1. Step 1
         1. carbamoyl P + ornithine > citruline
         2. ornithine transcarbamoylase
      2. Step 2
         1. citruline + D > argininosuccinate
         2. argininosuccinate synthase
      3. Step 3
         1. argininosuccinare <> arginine + fumarate
         2. arginosuccinase (argininosuccinate lyase)
      4. Step 4
         1. arginine > urea + ornithine
         2. arginase
6. Clinical Insights
   1. Inherited defects
   2. Liver damage
   3. Hibernation