6lx2

From Proteopedia

Potato D-enzyme complexed with CA26

Structural highlights

6lx2 is a 1 chain structure with sequence from Solanum tuberosum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.05Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

DPEP_SOLTU May act during starch breakdown to convert small oligosaccharides into larger molecules upon which starch phosphorylase can act, or may change the structure of starch molecules and grain architecture by modifying chain length, or may generate from starch and glucose oligosaccharides which can serve either as primers for new starch phosphoenzyme.

Publication Abstract from PubMed

Starch produced by plants is a stored form of energy and is an important dietary source of calories for humans and domestic animals. Disproportionating enzyme (D-enzyme) catalyzes intramolecular and intermolecular transglycosylation reactions of alpha-1, 4-glucan. D-enzyme is essential in starch metabolism in the potato. We present the crystal structures of potato D-enzyme, including two different types of complex structures: a primary Michaelis complex (substrate binding mode) for 26-meric cycloamylose (CA26) and a covalent intermediate for acarbose. Our study revealed that the acarbose and CA26 reactions catalyzed by potato D-enzyme involve the formation of a covalent intermediate with the donor substrate. HPAEC of reaction substrates and products revealed the activity of the potato D-enzyme on acarbose and CA26 as donor substrates. The structural and chromatography analyses provide insight into the mechanism of the coupling reaction of CA and glucose catalyzed by the potato D-enzyme. The enzymatic reaction mechanism does not involve residual hydrolysis. This could be particularly useful in preventing unnecessary starch degradation leading to reduced crop productivity. Optimization of this mechanism would be important for improvements of starch storage and productivity in crops.

Structural analysis and reaction mechanism of the disproportionating enzyme (D-enzyme) from potato.,Imamura K, Matsuura T, Nakagawa A, Kitamura S, Kusunoki M, Takaha T, Unno H Protein Sci. 2020 Aug 18. doi: 10.1002/pro.3932. PMID:32808707^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Imamura K, Matsuura T, Nakagawa A, Kitamura S, Kusunoki M, Takaha T, Unno H. Structural analysis and reaction mechanism of the disproportionating enzyme (D-enzyme) from potato. Protein Sci. 2020 Aug 18. doi: 10.1002/pro.3932. PMID:32808707 doi:http://dx.doi.org/10.1002/pro.3932