Discovery of a new type of sialidase, "KDNase," which specifically hydrolyzes deaminoneuraminyl (3-deoxy-D-glycero-D-galacto-2-nonulosonic acid) but not N-acylneuraminyl linkages.

Abstract

The release of 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN, deaminoneuraminic acid) residues from their alpha-ketosidic linkage is required to determine the structural and functional role of KDN-glycoconjugates in sources as disparate as trout egg polysialoglycoproteins and human cancers. We report for the first time the isolation and characterization of a novel type of sialidase (KDNase), which specifically hydrolyzes KDN ketosidic but not N-acylneuraminyl linkages. KDNase activity was assayed using 4-methylumbelliferyl KDN (4-MU-KDN). A KDNase-producing microorganism was identified as Sphingobacterium multivorum. The affinity-purified enzyme was designated KDNase SM to denote its origin and that it was free of N-acylneuraminidase, proteolytic, and other glycosidase activities. KDNase SM activity toward 4-MU-KDN was not inhibited by the N-acylneuraminidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. KDNase SM released free KDN from naturally occurring substrates, including (KDN)GM3, KDN-glycoprotein, which bears a number of O-linked chains of KDN alpha 2-->3Gal beta 1-->3GalNAc alpha 1-->3 (KDN alpha 2-->(-->8KDN alpha 2-->)n-->6)GalNAc alpha 1-->, and the biantennary complex-type of N-glycan, KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4GlcNAc beta 1-->4GlcNAc. KDNase SM thus exhibited a broad linkage specificity and was able to hydrolyze the KDN residues ketosidically linked alpha 2-->3, alpha 2-->6, and alpha 2-->8. The enzyme did not release Neu5Ac or Neu5Gc from 4-MU-Neu5Ac, N-acetyl-neuraminyllactose, colominic acid, or other Sia(Neu5Ac or Neu5Gc)-containing glycoconjugates.

• Authors: K Kitajima, H Kuroyanagi, S Inoue, J Ye, F A Troy 2nd, Y Inoue
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 269 Issue 34 Pg. 21415-9 (Aug 26 1994) ISSN: 0021-9258 [Print] United States
• PMID: 8063773 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cations, Divalent
• Glycoconjugates
• Glycosides
• Sialic Acids
• Sugar Acids
• 3-deoxyglycero-galacto-nonulosonic acid
• Neuraminidase
• N-Acetylneuraminic Acid

Topics

• Bacteria (enzymology)
• Carbohydrate Sequence
• Cations, Divalent (pharmacology)
• Chromatography, Affinity
• Glycoconjugates (metabolism)
• Glycosides (metabolism)
• Hydrogen-Ion Concentration
• Molecular Sequence Data
• N-Acetylneuraminic Acid
• Neuraminidase (antagonists & inhibitors, metabolism)
• Sialic Acids (metabolism)
• Substrate Specificity
• Sugar Acids (metabolism)