Isoamylase
| Isoamylase | ||
|---|---|---|
| other names |
|
|
| Mass / length primary structure | 1,532 AS , 174,764 Da (isoform 1) | |
| Identifier | ||
| External IDs |
|
|
| Enzyme classification | ||
| EC, category | 3.2.1.68 | |
| Occurrence | ||
| Homology family | HBG005824 | |
The isoamylase is an enzyme from the glycogen -Metabolism and catalyzes there specific hydrolysis .
properties
Isoamylase catalyzes the transfer of a D- glucan via an alpha-1: 4- glycosidic bond of glycogen to a glucose or a 1: 4-alpha-D-glucan. It also causes the hydrolysis of alpha-1: 6-branched glucose in glycogen, amylopectin and beta-bound dextrins . In contrast to pullulanase (EC 3.2.1.41) and limit dextrinase (EC 3.2.1.142), pullulan is not hydrolyzed, alpha-linked dextrins only slowly. In contrast to amylopectin-6-glucanohydrolase (EC 3.2.1.69), glycogen is hydrolyzed. Together with the activity of amylopectin-6-glucanohydrolase, the activity of the “debranching enzyme” arises. Different isoforms exist in humans . Human isoform 1 is phosphorylated at a serine at position 64 . A ubiquitination of isoamylase is at the origin of Cori's disease and Lafora disease involved.
The isoamylase in plants is involved in the formation of glycogen. Isoamylase gene defects lead to a lower build-up of starch and increased production of phytoglycogen .
literature
- MS Møller, A. Henriksen, B. Svensson: Structure and function of α-glucan debranching enzymes. In: Cellular and molecular life sciences: CMLS. Volume 73, Number 14, July 2016, pp. 2619-2641, doi : 10.1007 / s00018-016-2241-y , PMID 27137180 .
Individual evidence
- Jump up ↑ A. Cheng, M. Zhang, MS Gentry, CA Worby, JE Dixon, AR Saltiel: A role for AGL ubiquitination in the glycogen storage disorders of Lafora and Cori's disease. In: Genes & development. Volume 21, number 19, October 2007, pp. 2399-2409, doi : 10.1101 / gad.1553207 , PMID 17908927 , PMC 1993871 (free full text).
- ↑ James N. BeMiller: Starch. Academic Press, 2009, ISBN 978-0-080-92655-1 , p. 86.