NPN Biochemistry PDF

NPN Biochemistry ‫و عل ٌم ينتف ُع ِبه‬ Fares Tarek Definition and Types: Non-protein nitrogen (NPN) compounds are nitrogenous substances not precipitated by protein precipitating reagents, including: - Ammonia (NH3) - Urea - Uric acid - Creatine - Creatinine Ammonia...

NPN Biochemistry ‫و عل ٌم ينتف ُع ِبه‬ Fares Tarek Definition and Types: Non-protein nitrogen (NPN) compounds are nitrogenous substances not precipitated by protein precipitating reagents, including: - Ammonia (NH3) - Urea - Uric acid - Creatine - Creatinine Ammonia Metabolism: Sources: - Amino acid deamination - Purines and pyrimidines - Neurotransmitters - Intestinal bacterial urease - Monoamines and histamine metabolism Fate: - Main pathway: Urea formation in liver - Glutamine formation - Excretion in urine Ammonia Intoxication Causes: - Genetic: Urea cycle disorders - Acquired: - Liver dysfunction - Increased ammonia production - Renal failure - Infections - Medications/toxins Treatment: - Immediate protein intake reduction - Lactulose administration - Antibiotics - Ammonia scavenging agents - Hemodialysis in severe cases - Supportive care Urea Cycle: Process: - Occurs in both cytoplasm and mitochondria - Key enzymes: 1. Carbamoyl phosphate synthetase I (CPS1) 2. Ornithine transcarbamylase (OTC) 3. Argininosuccinate synthetase (ASS1) 4. Argininosuccinate lyase (ASL) 5. Arginase (ARG1) Energy Requirements: - Consumes 4 high-energy phosphate bonds - Net energy expenditure is one high-energy phosphate - Produces 2 NADH+H molecules Regulation: - CPS1 is the key enzyme - Requires N-Acetylglutamic acid as allosteric activator - Regulated by protein intake and amino acids, especially arginine Creatine and Creatinine: Creatine: Function: - Converted to phosphocreatine - Energy storage in muscles - Important during early stages of muscle exercise Levels: - Blood: 2-4 mg/dl (whole blood) - Urine: