Glycogen Synth and Degrad

Glycogen Synth and Degrad - Glycogen Synthesis and...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Glycogen Synthesis and Degradation if too little carbohydrate is supplied by the diet, glycogen reserves in liver and muscle tissue are mobilized Regulation of Glycogen Degradation o α-amylase (saliva, pancreatic secretions) – endoglcosidase; hydrolyzes α-1,4 linkages of glycogen and amylopectin; produce maltose, maltotriose, and small oliogsaccharides; leaves small highly branched saccharides (stops 4 residues away from any branching point) limit dextrins –highly branched polysaccharides left after α- amylase exposure; degraded by debranching enzymes glucanotransferase activity: transfer of trisaccharide unit from one branch to the end of another (α-amylase can act on this) glucosidase activity: hydrolyzes α-1,6 branch points o Digestion: highly efficient; unregulated (both catabolic and anabolic enzymes present in glycogen granules); thus, synthesis and degradation of storage glycogen must by highly regulated o Dietary and storage glycogens are digested through different pathways o Glycogen Phosphorylase – main enzyme of glycogen catabolism; cleaves 1 sugar unit from end of glycogen chain and uses P i to phosphorylate the glucose (avoids spending ATP to phosphorylate glucose) ; produce limit dextrins rxn is called phophorolysis b/c glycosidic bond is split by phosphate; ΔG = ~ 6 kJ/mol (b/c P i is in excess compared to glu-6- P in muscle, glu-6-P enters glycolysis; in liver, it’s hydrolyzed to glu to be transported to other tissues structure: 2 identical subunits w/ active and allosteric effector sites and towers; regulated by allosteric mechanism and covalent modification
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
o P i is positive homotropic effector
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/09/2010 for the course BIOL 3361 taught by Professor Zhang/spiro during the Fall '08 term at Dallas.

Page1 / 8

Glycogen Synth and Degrad - Glycogen Synthesis and...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online