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GLUCOGENÓLISIS (degradación del glucógeno) [pasos y regulación] | Metabolismo
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GLUCOGENÓLISIS (degradación del glucógeno) [pasos y regulación] | Metabolismo

Glucogenolysis: Breakdown of Glycogen

In this section, the process of glycogenolysis, which involves the breakdown of glycogen into glucose, is discussed. The enzymatic steps and regulation of this process are explained.

Steps in Glycogenolysis

  • Glycogenolysis involves breaking down glycogen to form glucose primarily in the liver and skeletal muscle.
  • The final step releases glucose into the blood; however, skeletal muscle lacks the enzyme to convert glucose-6-phosphate to free glucose.

Enzymatic Steps in Glycogenolysis

  • Glycogen is a polysaccharide with glucose residues that form alpha-1,4 and alpha-1,6 glycosidic bonds.
  • Enzyme glycogen phosphorylase initiates phosphorolytic cleavage of alpha-1,4 glycosidic bonds in glycogen.

Branching and Debranching Process

  • Every 10 to 14 glucose units have a branching point where enzyme debranching enzyme acts to remove branches by transferring three glucosyl units.

Regulation of Glycogenolysis

New Section

The discussion revolves around the regulation of glycogen breakdown through cyclic AMP levels and the role of hormones like insulin in this process.

Regulation of Glycogen Breakdown

  • Increasing cyclic AMP levels activates enzymes like glycogen phosphorylase and phosphorylase kinase, initiating glycogen degradation.
  • Glycogenolysis primarily occurs during fasting periods such as sleep and intense exercise.
Playlists: Metabolismo de carbohidratos
Video description

#glucógeno #glucogenólisis #ayuno ►Contenido: 0:00 Introducción 1:16 Pasos enzimáticos 5:54 Regulación 7:12 Resumen ►Datos adicionales: -Los gránulos de glucógeno también pueden ser engullidos por lisosomas, donde la maltasa ácida cataliza la hidrólisis del glucógeno a glucosa. Esto puede ser especialmente importante en la homeostasis de la glucosa en recién nacidos. -En eucariotas como en levaduras y humanos la enzima desramificadora contiene 2 sitios catalíticos: de transferasa y de glucosidasa. De hecho esta enzima, es la única en eucariotas que tiene dos sitios catalíticos y es activa como un monómero, es decir solo tiene estructura terciaria. En bacterias estas dos enzimas se encuentran separadas. -El glucagón está activo en el músculo cardíaco pero no en el músculo esquelético. ►Fuentes utilizadas para la elaboración del video: -Basu A, et al. Novel Insights Into Effects of Cortisol and Glucagon on Nocturnal Glucose Production in Type 2 Diabetes. The Journal of Clinical Endocrinology & Metabolism. 2020;105(7):e2378–88. -Cai Y, et al. Glycogenolysis Is Crucial for Astrocytic Glycogen Accumulation and Brain Damage after Reperfusion in Ischemic Stroke. iScience. 2020;23(5):101136. -Patino SC, et al. Biochemistry, Glycogenesis. Treasure Island (FL): StatPearls Publishing; 2021. -Zhang H, et al. Beyond energy storage: roles of glycogen metabolism in health and disease. FEBS Journal. 2021;288(12):3772-3783. -Vigh-Larsen JF, et al. Muscle Glycogen Metabolism and High-Intensity Exercise Performance: A Narrative Review. Sports Med. 2021;51(9):1855-1874. -Nadeau OW, et al. The regulation of glycogenolysis in the brain. Journal of Biological Chemistry. 2018;293(19):7099-7107.