Amino Acid Oxidation & Urea Cycle

   I. Background

  II. Dietary 
      A. Digestion
         1. gastrin
            a. pepsinogen
               1) pepsin
         2. food in SI
            a. secretin
            b. cholecystokinin (CKK)
                  a) trypsinogen
                     - trypsin
                   b) chymotrypsinogen
                     - chymotrypsin
            c. intestinal wall cells
               1) carboxypeptidases A & B
               2) aminopeptidases
      B. Acute pancreatitis

 III. Amino Acid Oxidation Liver
      A. Step 1
         1. aminotranferases
            a. pyridoxal phosphate
      B. Step 2
            a. oxidative deamination
         1. glutamate dehydrogenase

  IV. Protein breakdown
      A. Transport forms
         1. glutamine synthetase
         2. Glucose-alanine cycle
            a. alanine aminotransferase

   V. Ammonia bad

  VI. Urea cycle
      A. Excretory strategies
         1. Ammonotelic
         2. Ureotelic
         3. Uricotelic
      B. Pre-step
         1. carbamoyl phosphate
            a. carbamoyl phosphate synthase I (CPS I)
      C. Urea cycle
         1. Step 1
            a. carbamoyl P + ornithine -> citruline
            b. ornithine transcarbamoylase
         2. Step 2
            a. citruline + D -> argininosuccinate
            b. argininosuccinate synthase
         3. Step 3
            a. argininosuccinare <-> arginine + fumarate
            b. arginosuccinase (argininosuccinate lyase)
         4. Step 4
            a. arginine -> urea + ornithine
            b. arginase

 VII. Clinical Insights
      A. Inherited defects
      B. Liver damage
      C. Hibernation