THE SUBSTRATE-SPECIFICITY OF THE ENZYME ENDO-ALPHA-N-ACETYL-D-GALACTOSAMINIDASE FROM DIPLOCOCCUS-PNEUMONIA

Citation
Mm. Brooks et Av. Savage, THE SUBSTRATE-SPECIFICITY OF THE ENZYME ENDO-ALPHA-N-ACETYL-D-GALACTOSAMINIDASE FROM DIPLOCOCCUS-PNEUMONIA, Glycoconjugate journal, 14(2), 1997, pp. 183-190
Citations number
29
Categorie Soggetti
Biology
Journal title
ISSN journal
02820080
Volume
14
Issue
2
Year of publication
1997
Pages
183 - 190
Database
ISI
SICI code
0282-0080(1997)14:2<183:TSOTEE>2.0.ZU;2-G
Abstract
The substrate specificity of the enzyme endo-alpha-N-acetyl-D-galactos aminidase from Diplococcus pneumonia was re-examined using bovine subm axillary mucin and remodelled antifreeze glycoprotein as substrates. I ncubation with desialylated bovine submaxillary mucin, which contains six O-linked core types, indicated that the disaccharide Gal beta 1-3G alNAc, which is present in very small amount, was the only glycan rele ased, while the disaccharide GlcNAc beta 1-3GalNAc, which is the major structure present, and other disaccharides, were not released. To tes t whether the core disaccharide Gal beta 1-3GalNAc with sialic acid li nked alpha 2-3 to the Gal or linked alpha 2-6 to the GalNAc was releas ed, the enzyme was Incubated with remodelled antifreeze glycoprotein c ontaining (1) [H-3]NeuAc alpha 2-3Gal beta 1-3GalNAc and (2) Gal beta 1-3[[C-14]NeuAc alpha 2-6]GalNAc as substrates. No NeuAc-containing tr isaccharide was released. These results serve to clarify the doubts of many researchers regarding the activity of this enzyme on some newly- described core types and on sialylated substrates.