Change search
ReferencesLink to record
Permanent link

Direct link
Mutated barley (1,3)-beta-D-glucan endohydrolases synthesize crystalline (1,3)-beta-D-glucans
Show others and affiliations
2002 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 277, no 33, 30102-30111 p.Article in journal (Refereed) Published
Abstract [en]

Barley (1,3)-beta-D-glucan endohydrolases (EC, inactivated by site-directed mutagenesis of their catalytic nucleophiles, show autocondensation glucosynthetic activity with alpha-laminaribiosyl fluoride and heterocondensation glycosynthetic activity with a-laminaribiosyl fluoride and 4'-nitrophenyl beta-D-glucopyranoside. The native enzyme is a retaining endohydrolase of the family 17 group and catalyzes glycosyl transfer reactions at high substrate concentrations. Catalytic efficiencies (k(cat) K-m(-1)) of mutants E231G, E231S, and E231A as glycosynthases are 28.9, 0.9, and 0.5 x 10(-4) M-1 s(-1), respectively. Glycosynthase reactions appear to be processive and proceed with pH optima of 6-8 and yields of up to 75%. Insoluble products formed during the glycosynthase reaction appear as lamellar, hexagonal crystals when observed by electron microscopy. Methylation, NMR, and matrix-assisted laser desorption ionization time-of-flight analyses show that the reaction products are linear (1,3)-beta-D-glucans with a degree of polymerization of 30-34, whereas electron and x-ray diffraction patterns indicate that these (1,3)-beta-D-glucan chains adopt a parallel, triple helical conformation. The (1,3)-beta-D-glucan triple helices are orientated perpendicularly to the plane of the lamellar crystals. The barley (1,3)-beta-D-glucan glycosynthases have considerable potential for tailored and high efficiency synthesis of (1,3)-beta-D-linked oligo- and polysaccharides, some of which could have immunomodulating activity, or for the coupling of (1,3)-beta-D-linked glucosyl residues onto other oligosaccharides or glycoproteins.

Place, publisher, year, edition, pages
2002. Vol. 277, no 33, 30102-30111 p.
Keyword [en]
catalytic amino-acids, packing analysis, cdna clone, in-vitro, substrate, polysaccharides, purification, (1->3)-beta-d-glucans, (1->3)-beta-glucan, glucosidase
URN: urn:nbn:se:kth:diva-21831ISI: 000177509300093OAI: diva2:340529
QC 20100525Available from: 2010-08-10 Created: 2010-08-10Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Bulone, Vincent
By organisation
In the same journal
Journal of Biological Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 30 hits
ReferencesLink to record
Permanent link

Direct link