Notes on Carbohydrate Metabolism

Notes On Carbohydrate Metabolism Digestion of carbohydrates Halts temporarily in stomach. Sucrose → glucose + fructose Hel 1- Pancreatic amylase is called "amylapsin" PH27.1 2- Digestion is completed by Pancreatic anglese due to longer time of food in intestine. 3- Sucrase isomaltase Bifunctional enzyme n Sucrose isomaltose Suchanfase 3 Glucose fructose 4- Abnormal digestion of disaccharides leading to "Osmotic diarrhea + bacterial fermentations lactose intolerance defect in chromosome 2 n treatment: Yogurt cheese, braceli + lactase Pills. lactase B-galactosidase work at PH = 5.4 to 6 Inducible lactose intolerance. -Treated by card" Congenital primary of lactase Acquired during lifetime After birth asians precipitated by milk feed Primary Mucosal damage is caused by intestinal Parasites like e Giardia lamblian that can be permanent. Rotavirus or celiac disease can cause temporary mucosal damage. Diagnosis of lactose intolerance: Hydrogen breath test 2-3 hours after milk intake. Stool acidity test. Positive urine Benedictus test due to "lactosuria" Mucosal biopsy-confirm diagnosis" *Note: Benedict's test is not positive in "sucrase-isomaltase deficiency" because Sucrose is non-reducing sugar. 6- Glucose transporters: GLUTs GLUT1: RBC, brain, kidney, retina GLUT2: Neurons, brain. GLUT3: intestine, testis GLUT4: liver SER for glucose entry to cytosol. SGLUT1: Intestine" SGLUizkidney». Pentoses are absorbed by Slow Passive diffusion" Defect of Salut causes "galactosuria malabsorption" Defect of SGLUT2: Glycosuria". Insulin induce movement of GLUT4 to the cell surface. In Dm, entry of glucose to muscle is 50%.. Aldosterone, thyroid hormones ↑ glucose absorption. 7 GLUT facilitated transporters in peripheral tissue, Cancer cells use GLUT-1 to uplake glucose GLUT4 is non functional, produced by pse-dogene. 5% of glucose is converted to other sugars Amphibolic Pathing" Putatine gene" Glycolysis Glucokinase function as sensor for insulin secretion Hexokinase in hypothalamus causes adrenergic response to hypoglycemia. Maturity onset of young type 2 (MODY2) is caused by mutations that ↓ glucokinase activity. Fasting blood sugar (FBS) 60-110 mg/dl Average 90 mg/dl SI Unit → mg/dl x 10, means 40 x 10 = 5 mM 180 Glycolysis 30% of energy, TCA 70% energy Post prandial glucose is below 150 mg/dl Glucose phosphorylation is called "priming reactions" to trap glucose and to keep it low inside the cell. Hexokinase has "low affinity" to fructose-galactose, Km=0.05 MM/L E.g.: mannose Hexokinase → mannose 6-phosphate → fructose 6-P isomerase Step 1,2,3 in glycolysis are called "preparatory phase" 2,3 BPG shunt is called "Rapa Port-Leubering cycle" bypass the SLP No ATP productions. Hypoxia, altitude, anemia, fetus, smoking ↑ 2,3 BPG, 4-5 mM 2,3 BPG stabilize T-form of Hb → O2 release 2,3 BPG binding to fetal Hb is difficult because of lacking histidine in β subunit. That is cause O2 flows from mother to fetus Fetal blood has higher or affinity than maternal blood. Add flouride when taking blood for sugar estimation to Stop RBC glycolysis. ILDHS Hepatitis n LDH-has 5 isoenzymes LDH1 Tin M.I LDH is abottleneck step ta reconvert NADHsh to NAD. The anaerobic glycolysis is called fermentation" lactate serve as fuel for heart, brain. Astrocytes produce lactate, neuron convert it to Pyruvate. Glucose ↑ Carbohydrate responsive element binding Protein "ChREBP", which bind DNA and "↑ Pyruvate kinase" transcription ChREBP gene Response ↓↑ Transcription - induction element RNA "Pyruvate Kinase" Pyruvate kinase & hexokinase deficiency → Hemolysis ↑2,3BPG, ↓O2 Aldolase deficiency → Hemolysis PFK.1 deficiency → muscle weakness Pyruvate dehydrogenase deficiency → beriberi and lactic acidosis. Notes on Carbohydrate Metabolism - Part II - 2019 About Introduction of CHO: Inulin is fructose polymer from garlic and onion used for pe kidney function, measure GFR Dextrans bacteria & yeast Dental Plaque Chitin - insects exoskeleton Polymer of N-acetylglucosamine. B(224) Heparin is anticoagulant GAGS" lectin is protein bind to carbohydrate receptors • used for purification and analysis of glycoproteins About CH2O metabolism: P.D P.D Kinase P.D Inactive Defect is X-linked EEE ATP NADH dominant male, female acetylcom *Brain and starvation: 60-70% of energy is from ketone bodies → Hypoglycemia below 30 mg/dl is fatal About T.C.A: leucine, lysine ketogenic acetylcoA → T.C.A Notes on Carbohydrate Metabolism - Part II - 2019 About Introduction of CHO: Inulin is fructose polymer from garlic and onion used for pe kidney function, measure GFR Dextrans bacteria & yeast Dental Plaque Chitin - insects exoskeleton Polymer of N-acetylglucosamine. B(224) Heparin is anticoagulant GAGS" lectin is protein bind to carbohydrate receptors • used for purification and analysis of glycoproteins About CH2O metabolism: P.D P.D Kinase P.D Inactive Defect is X-linked EEE ATP NADH dominant male, female acetylcom *Brain and starvation: 60-70% of energy is from ketone bodies → Hypoglycemia below 30 mg/dl is fatal About T.C.A: leucine, lysine ketogenic acetylcoA → T.C.A lencing glucose Fatty acids lysine Not produce Acetylcon ketone bodies. glucose or cholesterol or fatty acids TCA * ATP generating steps. in T.c.A 3NADI+H = 3X2.5 2 FADH = IX 1.5 7.5 1.5 33% ATP heat 1 ATP1 = 1 To ATP New * Fat is burned in wick of carbohydrate Fat → acetylcol CHzo Pyruvate OAA Co major Catalyاد T.C.A • Anaerobiasis Hypoxia E.T.C • lactis acilosis. Causes TNADHH FADHT.C.A flouro acetate, arsenite are non competitive inhibitors" About G.N.G① Pyruvate carboxylase Anarlexdic ②PEPCK Fructose 1.6 bisphosphatese Glucose-6-Phosphatase.. Alanine use Malate shuttle lactate glucose use aspartate shittle gluarse Alanine kycle is related to cori gele starvation? •Propionfor Succinglara malate. val, met, Ile cytosol Reciprocal regulation of G.N.G: Insulin, Glucagon, Cortisol, Epinephrine, Acetyl CoA, Citrate Futile Cycle or Substrate Cycle: When two opposite metabolic pathways occur in the same time. Release energy as heat. E.g.: Glycolysis and G.N.G Acetyl CoA activate Pyruvate carboxylase to produce oxaloacetate during starvation (Anaplerotic) About HMP Shunt: NADPH reduces Met Hb to Hb Fe3+ G6PD → hemolysis and met hemoglobinemia TPP Transketolase → Wernicke Korsakoff Syndrome UDP-Glucuronic acid for: GAGS, Conjugation of bilirubin, Steroids Lower animals have oxidase, not in human → L-Gulonolactone → Ascorbic acid (Vit. C) Classic galactosemia (GALT): Cataract, jaundice and mental retardation, Silent amino aciduria. Detected by amniocentesis & prenatally Lactose free diet up to 4 years old.