1 / 29

Glycogen

Glycogen. ~. Human liver - 50 g/kg wet wt. ~. Skeletal muscle - 15 g/kg wet wt. Glycogenin = protein core Glycosome.  1-4 bonds 1-6 bonds Glycoside bonds. Tier 8. Proglycogen (acid insoluble) Macroglycogen (acid soluble). Size = glycogenin – Proglycogen – Macroglycogen

jaden
Download Presentation

Glycogen

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Glycogen

  2. ~ Human liver - 50 g/kg wet wt. ~ Skeletal muscle - 15 g/kg wet wt. Glycogenin = protein core Glycosome

  3.  1-4 bonds • 1-6 bonds Glycoside bonds

  4. Tier 8 Proglycogen (acid insoluble) Macroglycogen (acid soluble) Size = glycogenin – Proglycogen – Macroglycogen 12 tiers is the maximum – branches too dense to allow GS

  5. Two Forms of Muscle Glycogen Proglycogen Macroglycogen Glygogenin Lomako, et al., FASAB J. 9, 1126-1137, 1995 75% proglycogen/25% macroglycogen

  6. Glycogen SynthesisGlycogen Synthase 1-4 bonds Glycosyl 4:6 transferase Branching enzyme (at least 11) (move at least 7) ( leave at least 4)

  7. Glycogenolysis 1-6 Bond 1-4 Bond (Glucose-1-P Glucose-6-P) (phosphoglucomutase) phosphorylase Glucose -6-P a b c d e f a b c glycosyl 4:4 transferase (breaks a 1-4, makes a 1-4) to glycolysis (NEXT)

  8. Glycogenolysis (cont.) a b c d e f a b c glycosyl 4:4 transferase a b c d e f to another chain a b c Amylo 1:6 glucosidase free glucose free glucose

  9. Summary Glycogenolysis- the break down of glycogen into glucose Glycogen Synthesis- the storage of glucose via glycogen formation -Glycogen Synthase- enzyme responsible for making  1-4 bonds between glucose molecules -Glycosyl 4:6 transferase- enzyme that breaks  1-4 bonds, and makes  1-6 bonds to allow for branching

  10. Skeletal Muscle Epi/N-Epi (beta receptor)  C-AMP  Ca++ (actives phosphorylase kinase These will increase activity of phosphorylase and decrease glycogen synthase Insulin  PDE activity which will decrease C-AMP  PP-1 which will increase the activity of GS and decrease the activity of phosphorylase Summary

  11. Three CHO-Loading Protocols: Two Depletion & One Taper Saltin and Hermansen, Nut. Physical Activity, pp.32-46, 1967

  12. Phosphorylates glycogen synthase

  13. CA++ actives Phosphorylase Kinase at the start of exercise by 20x. Ca++ binds to gamma subunit of PK. Phosphorylase Kinase activated via C-AMP and PKA. Phosphorylase kinase phosphorylates Phosphorylase at serine 14. AMP allosterically actives Phosphorylase.

  14. Inactive Active - P Insulin activates PP-1 and PDE (phosphodiesterase). This will decrease C-AMP and dephosphorylate proteins that were phosphorylated by PKA

  15. Order of Glycogen Resynthesis Lomako, et. al.,FASAB 7:1386-1393

  16. Glycogen Storage Diseases Type I: Von Gierke Disease; Glucose-6-phosphatase Defect • Hypoglycemia occurs due to defect of the final step of gluconeogenesis. • This disease, affects only liver and renal tubule cells • Decreased mobilization of glycogen produces hepatomegaly. Type V: McArdle Disease; Skeletal Muscle Glycogen Phosphorylase Defect • Skeletal muscle is affected, whereas the liver enzyme is normal. • Exercise capacity is greatly reduced, hypoglycemia during exercise • There is no rise in blood lactate during strenuous exercise. • Muscle contains a high level of glycogen with normal structure • Type VI: Hers Disease; Liver Glycogen Phosphorylase Defect • Liver is affected, whereas the skeletal muscle enzyme is normal. • Marked hepatomegaly occurs due to a high level of glycogen with normal structure.. • Following administration of glucagon, there is no increase in blood glucose.

  17. Slow Phase- dependent on insulin concentration Rapid Phase – increased insulin sensitivity GLUT 4 from exercise Casey, et al., J.Physiol. 48(1): 265-271, 1995.

  18. EFFECT of DETRAINING on MUSCLE GLYCOGEN CONCENTRATIONS 100% 80% 72% 60% Costill, et., al., Med. Sci. Sports Exerc., 17(3):339-343, 1985.

  19. Muscle Glycogen During 3 days of Endurance Training and al Low-CHO vs High-CHO Diet Costill, et. al., J.A.P. 31(6): 834-838, 1971.

More Related