Biochemistry

Now Serving: The Lettuce

- the crunch you get from fresh lettuce

We are back from the Common Test week and will continue update this space! :D

Let's start off with the Biochemistry of Glycogen

Glycogen is principally found in muscle and liver cells, where it is stored as an energy source readily converted into glucose whenever our body requires energy. When muscle cells require energy, glycogen will be converted to ATP.

As seen from the picture, glycogen is actually comprised of linked alpha-D-glucose monomers that form linkages by either alpha-1,4 or alpha-1,6 linkages.

Glycogen Breakdown

Glycogen is broken down by glycogen phosphorylase. The reaction is non hydrolytic as water molecules are not produced upon the breakdown. Glycogen phosphorylase combines inorganic phosphate with the non reducing terminal glucose residue to form glucose-1-phosphate. 

Disease

When someone actually contracts McArdle's Disease, they're ability to synthesize glycogen phosphorylase is not impaired, but due to mutations in the gene coding for Myophosphorylase, they are unable to execute their normal function of breaking down glycogen into glucose, as such, mucles are deprived of glucose with is then converted to ATP via other metabolic pathways, which thus leads to accelerated muscle fatigue and glycogen remains accumulated in muscle tissues, hence the name Glycogen Storage Disease.

References
https://www.uic.edu/classes/phar/phar332/Clinical_Cases/carbo%20metab%20cases/glycogen%20metab/Glycogen%20biochemistry.htm

http://medicinembbs.blogspot.sg/2011/02/genetic-diseases.html

http://www.nlm.nih.gov/medlineplus/ency/article/000329.htm

http://en.m.wikipedia.org/wiki/Glycogen_storage_disease_type_V

http://mcardlesdisease.org/

http://www.patient.co.uk/doctor/mcardles-disease-glycogen-storage-disease-type-v