fast and efficient. releases G-1-P only if at least 5 units from branch point. has a very large active site. can handle 4-5 glycogen molecules. branch point prevents it from moving down the chain. Activators: hormones (glucagon, epinephrine), AMP, phosphorylation. Protein Kinase A activates phosphorylase kinase, Ca2+ activates glycogen phosphorylase. Inhibitors: ATP, G1P/G6P, insulin, glucose
glycogen debranching enzyme
slow. removes branches and puts them at nonreducing end of another chain, making additional glucose residues accessible to glycogen phosphorylase. Transfers an alpha 1->4 trisaccharide unit from a limit branch to the nonreducing end of another branch. 10% of residues converted to glucose instead of G1P. Slow - rate limiting step
converts G1P to G6P to be used for other pathways
Allows addition of G1P to glycogen. Primes glucose for addition to glycogen. UDP-glucose is a high energy molecule. glucose-1-phosphate + UTP -> UDP-glucose + pyrophosphate
Actual addition of glucose to glycogen (only alpha 1->4). 1 molecule of UTP is cleaved to UDP for each glucose. Activators: G6P. Inhibitors: ATP, ADP, Pi, phosphorylation. Activity varies with [G6P]. primed by glycogenin.
Takes UDP-glucose and adds it to its tyrosine group. Extends glucose chain by up to 7 additional UDPG-donated glucose molecules to form glycogen primer. Then glycogen synthase extends primer
Glycogen Branching enzyme
Transfers 7 unit segment from one end of one chain to C6-OH of another glucose on the same or another glycogen chain. Each segment must come from a chain of at least 11 residues. New branch point must be 4 residues away from another branch point
Liver Glycogen Synthase Deficiency
Type 0. Glycogen normal but deficient. Hyperglycemia after meals, hypoglycemia at all other times. Some asymptomatic
Von Glerke's disease
Type I. Glucose-6-phosphatase deficiency. Results in increase of intracellular [G6P] (because it can't leave the liver) -> accumulation of glycogen in liver and kidney and inability to increase blood [glucose] in response to glucagon and epinephrine. Hepatomegaly, hypoglycemia, failure to thrive. Affects liver. Glycogen normal. Weak, not much energy, have to eat a lot
Type IV. branching enzyme deficiency. rarely survive past 4 because of liver dysfunction. glycogen contains long unbranched chains - reduces its solubility.
Type V. Muscle Phosphorylase Deficiency. painful muscle cramps on exertion. avoid strenous exercise. can't break down glycogen in muscle.
Type VI. Liver Phosphorylase Deficiency. hypoglycemia. inability of liver glycogen phosphorylase to respond to the need for circulating glucose.
type III. debranching enzyme deficiency. outer chains missing/very short. hypoglycemia. frequent feedings and high protein diet.
Glucose 6-phosphate + NADP -> 6-phosphoglucono-δ-lactone + NADPH. 1st committed step. inhibitors: high [NADPH]. mamor source of NADPH. activated by thioredoxin by PS1. (PPP)
6-phosphogluconate + NADP -> ribulose 5-phosphate + NADPH + CO2. makes 2nd NADPH and converts 6C -> 5C + CO2. reverse of rubisco. (PPP)
inactivates peroxides. reduces free radical change.
enzyme catalyzing the second step in beta oxidation: removal of a double bond by the addition of water
enzyme catalyzing the activation of the fatty acid in which ATP is converted AMP + PPi
carnitine acyltransferase I
enzyme that transfers the fatty acyl group from CoA to a carrier molecule
site of beta-oxidation, TCA cycle, and ETC
first step of beta oxidation. transfers electrons from fatty acyl-CoA to FAD
carrier compound required for the transport of fatty acids across the inner mitochondrial membrane
B5; forms coenzyme A
B2; source of FAD which fuels ATP production
also called niacin; precursor of NADH which is the main source of electrons for ATP production
B6; required for utilization of amino acids for energy
B1; ____ pyrophosphate is used for aldehyde transfer
Beriberi; can cause weight loss, confusion, muscle wasting, enlargement of heart
fissuring at corner of mouth, dermatitis, behavioral change
Pellagra; weakness, insomnia, impaired digestion, irritability, memory loss
panthotentic acid deficiency
vomiting, malaise, fatigue, cramps, abdominal cramps
reduced form; reducing agent (reductant); ends as oxidized
oxidized form; oxidizing agent (oxidant); ends as reduced