Glucose 6-phosphate - Wikipedia
Glucose-1-phosphate is converted into glucose-6-phosphate catalyzed by an enzyme phosphoglucomutatse as described above
Demonstration of a Glycogen/Glucose 1-Phosphate …
entry to cell is insulin-independent Galactose Galactose 1P UDP-Galactose Galactose 1P
uridyltransferase Galactokinase UDP-hexose
4-epimerase Lactose Glycoproteins
Glycosaminoglycans Lactose Lactase
(B-galactosidase) Galactitol Aldolase reducatase present in liver, kidney, retina, lens, nerve, seminal vesicles, and ovaries
physiologically unimportant unless galactose is high
elevated galactitol can cause cataracts Galactokinase deficiency
Causes galactosemia and galactosuria
Causes galactitol accumulation if galactose present in diet Classic galactosemia
Autosomal recessive (1:23k births)
Causes galactosemia and galactosuria, vomiting, diarrhea, and jaundice
Accumulation of Gal-1-P in nerve, lens, liver, and kidney tissue causes liver damage, severe mental retardation, and cataracts
Antenatal diagnosis is possible by chorionic villus sampling
Treatment: Rapid diagnosis and removal of galactose (therefore, lactose) from diet synthesis in mammary glands in intestinal mucosa cell membrane G6Pase not found in muscle cells consumes energy Arginosuccinate Arginine Aspartate Urea Carbamoyl-P Citrulline NH3 Ornithine CO2 glutamate a-keto acid a-amino acid aminotransferases transamination -ALT forms pyruvate from Ala
-AST shuttles N from Glu to Asp
during AA catabolism (Asp to urea cycle) all require pyridoxal phosphate
(deriv of vit B6) Clinical correlation: aminotransferases in blood indicate damage to cells.
-Liver disease: elevated plasma AST and ALT
-Other: myocardial infarction and muscle disorders Glutamate dehydrogenase oxidative deamination NAD+ or
NADP+ NH3 NAD+ primarily used in oxidative deamination
NADPH used in reductive amination ATP
GDP Ammonia transfer to liver
-Glutamine synthetase in most tissues produces Gln which is transported in blood to liver, where glutaminase cleaves Gln producing Glu and NH3.
-Transamination of pyruvate in muscle forms alanine which is transported in blood to liver.
hi F26BP Remember: 2x per glucose from here on down "substrate-level phosphorylation" Feed-forward regulation cAMP-dependent phosyl'n
--> PEP to gluconeogenesis PK deficiency (autosomal recessive) is second most common cause (after G6PDH def.) of enzyme-related hemolytic anemia
restricted to RBCs
severe chronic HA requires regular cell transfusions
partially compensated for by increased production of 23BPG Pyruvate
Carboxylase CO2 TCA and FA synthesis Oxaloacetate Malate Fumarate Succinate Succinyl Co-A alpha-Ketoglutarate Isocitrate Citrate Tri-Carboxylic
Acid Cycle Citrate Synthase Fumarase Isocitrate
Dehydrogenase Succinyl CoA
Synthetase aKG Dehydrogenase
Complex Aconitase mitochondrial
Dehydrogenase H2O CoA-SH CO2 NADH CO2 NADH CoA-SH CoA-SH GTP FADH2 H2O NADH Cytosol Mitochondrion Pyruvate transporter Pyruvate NADH NAD+ Co-A NADH, ATP,
and Ac-CoA Component enzymes: multiple copies of each in tight physical association
-pyruvate dehydrogenase, E1, decarboxylase --> requires TPP
-dihydrolipoyl transacetylase, E2 --> requires lipoic acid and Co-A
-Dihydrolipoly dehydrogenase, E3 --> requires FAD and NAD+ Phosphoprotein phosphatase -dephosphorylates E1 in presences of Ca+2 cAMP-independent protein kinase -phosphorylates E1 in presence of Ac-CoA, ATP, NADH -PK inhibited by pyruvate (thereby activating E1) NAD+ ATP Malate cytosolic
Dehydrogenase Oxaloacetate cytosolic
PEP Carboxykinase Occurs in liver and kidney
Uses biotin as a coenzyme
-provide substrate for gluconeogenesis
-replenish TCA cycle intermediates
Muscle pyruvate carboxylase forms OAA only to replenish TCA
OAA cannot cross mitoch.
Glycogen n-----> Glucose-1-Phosphate + Glycogen n-1; ..
AMP binds directly to muscle glycogen phosphorylase, causing activation without phosphorylation.
Glucose + glycogen phosphorylase B can not be allosterically activated by AMP Glucose + glycogen phosphorylase A is better substrate for protein phosphatase 1 --> glycogen degradation not required Insulin inhibits muscle glycogen phosphorylase by increasing uptake of glucose --> increase in G6P levels --> allosteric inhibition of glycogen phosphorylase P Inactive Glycogen
phosphorylase B Phosphorylase
Kinase A (active) P Phosphorylase
Kinase B (inactive) cAMP-dependent
Protein Kinase Protein Phosphatase 1 Glucagon
Epinephrine Protein phosphatase 1 ATP ATP Insulin Insulin Glycogen synthase B
(inactive) P cAMP-dependent
(A & C) Glucagon
Phosphatase 1 Insulin Fructose Fructose
1-Phosphate Fructokinase low affinity for fructose liver, kidney, small intestine ATP Aldolase B
small intestine Glyceraldehyde Triokinase ATP Glycerol Glycerol-P Alcohol
Dehydrogenase NADH Glycerol
Kinase ATP Phosphoglycerides Triacylglycerides Hexokinase ATP Sucrose in small intestine Sucrase Essential fructosuria
Lack of fructokinase
Autosomal recessive (1:130k births)
Benign, asymptomatic condition
Fructose accumulates in urine Hereditary fructose intolerance
Absence of aldolase B --> intracellular trapping of F1P
Hypoglycemia, vomitting, jaundice, hemorrhage, hepatomegaly, and hyperuricemia
Can cause hepatic failure and death
Therapy: Rapid detection and removal of fructose and sucrose from the diet Mannose Mannose 6P Hexokinase Phosphomannose isomerase ATP Glucose Sorbitol Aldolase reductase Found in: lens, retina, Schwann cells, liver, kidney, placenta, RBCs, ovaries, sperm, and seminal vesicles Sorbitol dehydrogenase Found in: liver, ovaries, sperm, and seminal vesicles
Sperm use fructose as major CHO energy
Liver can convert any available sorbitol to glycolytic intermediate NADPH NADPH Sorbitol cannot pass efficiently through cell membranes, so when it is formed in hyperglycemic conditions (DM) with little or no sorbitol DHase (such as in the lens, retina, kidney, and nerve cells), it can cause swelling as a result of water retention.
So, cells gradually break down glucose in a whole series of reactions & use the smaller amounts of energy released in these reactions to produce from ADP (Adenosine Diphosphate).
UDP glucose phosphorylase acts on glucose 1 phosphate ..
2 ATP Carbamoyl phosphate
synthetase I N-acetyl-glutamate
absolutely required Citrulline Ornithine Fumarate Ornithine trans-
synthetase ATP AMP Arginosuccinate
lyase Arginase Urea Cycle Malate Glutamate Oxaloacetate a-ketoglutarate a-ketoglutarate Pi Glucose To mitochondria and TCA via the malate shuttle almost exclusively in the liver to kidney via blood Some urea diffuses from blood to intestine where bacterial urease cleaves it to CO2 and NH3.
-In patients with kidney failure, a greater amount of urea is transfered to the gut, and bacterial urease contributes significantly to hyperammonemia.
The bacterial glycogen phosphorylase is a pyridoxal phosphate enzyme that transform glycogen to glucose 1-phosphate, which is then transformed to glucose-6-phosphate, a normal intermediate of glycolysis.
Glossary | Linus Pauling Institute | Oregon State University
SparkNotes: Glycolysis: Stage 1: Glucose Breakdown
31/10/1993 · Demonstration of a Glycogen/Glucose 1-Phosphate Cycle in Hepatocytes from ..
Gluconeogenesis: definition, steps, regulation, and …
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College of Natural & Behavioral Sciences
Glycogen - Wikipedia
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