ID: 0070573
Spring 2011
region and Conserved sequences of Glycogen Phosphorylase
Glycogen phosphorylase belongs to a super family glycosyltransferease. It function is cleave a glucose from animal starch at the 1-4 alpha glycosidic bond which is the first and rate limiting pace in abjection of animal starch (?-1,4-glucoside)n + Pi (? - 1,4-glucoside)n-1 + ?-glucose-1-P. It is a homodimer and individually subunit consists of about 850 residues with a site for glycogen storage, an industrious site and two allosteric sites. The active site of glycogen phosphorylase is buried deep inside the protein and provides a hydrophobic environment for degradation of glycogen. This environment prevents water from degradation of glycogen into glucose and glycogen slight one monomer. The main product of glycogen degradation is glucose-1-phosphate. some(prenominal) glycogen and glucose-1-phophate products are both in the ? forms, a carbocation middling is necessary otherwise a Sn2 type of phospholysed would form the ? glucose-1-phosphate. At the active site, the aldehyde of pyridoxal phosphate (PLP) coenzyme forms a Schiff base with Lys681 (the ground tackle sequence used is human liver form glycogen phosphorylase UniProt ID P06737).
The 5-phosphate group of PLP can give a proton to an orthophosphate (HPO4-2) and at the very(prenominal) time the orthophosphate then can donate its other proton the oxygen of the leaving glycogen. Once protonated, the leaving glycogen breaks away and leave behind a carbocation glucose and a PLP indentured orthophosphate anion. The orthophosphate anion now is able to protonated the PLP and at the same time form an ? bond with the carbocation glucose and the product ?-glucose-1-phosphate is produced (Michelle.)
(picture from Intro to Structure, Function and Informatics - C. Tsai Wiley, 2007)
To held the orthophosphate and the phosphate of PLP in appropriate orientation, three hydrogen bonds is formed between Lys569, the peptide bond between Gly136 and Gly135,...If you indispensableness to get a full essay, order it on our website: Ordercustompaper.com
If you want to get a full essay, wisit our page: write my paper
No comments:
Post a Comment