endohydrolysis of N-acetylglucosaminyl linkages in keratan, releasing beta-D-Gal-(1->4)-GlcNAc disaccharides with one or two sulfo groups, or tetrasaccharides beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-GlcNAc
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
endohydrolysis of N-acetylglucosaminyl linkages in keratan, releasing beta-D-Gal-(1->4)-GlcNAc disaccharides with one or two sulfo groups, or tetrasaccharides beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-GlcNAc
compared with cornea keratan sulfate, keratan sulfates from human nucleus pulposus and shark cartilage are attacked at lower rates with a resultant production of oligosaccharides of relatively large size. The point of enzyme attack is limited to the endo-beta-D-galactoside bonds in which nonsulfated D-galactose residues participate. The bond susceptible to hydrolysis is associated with beta-D-Gal-(1->4)-2-acetamido-2-deoxy-6-O-sulfo-n-glucose in keratan sulfate. The major oligosaccharide products in the digest are terminated by galactose and 2-acetamido-2-deoxy-6-O-sulfoglucose at the reducing and nonreducing end, respectively
the enzyme hydrolyzes the beta1-3-glucosaminidic linkages to galactose in keratan sulfate, when the 6-O-position of GlcNAc is sulfated. It degrades not only B type 2-type 2 keratan sulfate but also type 1-type 2 keratan sulfate, significantly
hydrolyzes keratan sulfate between the 4GlcNAcbeta1-3Gal1 structure, digests shark cartilage keratan sulfate to disaccharides and tetrasaccharides and bovine cornea keratan sulfate to hexasaccharides, prefers highly sulfated keratan sulfate
the enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Gal-beta-(1->4)-[Fuc-alpha-(1->3)]-GlcNAc(6-OSO3-)) (su-Lex) soxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields. Exclusive formation of the beta-(1->3) glycosidic bond
transglycosylation to form beta-(1->3)-glycosidic bond through a substrate-assisted mechanism. N-Acetyllactosamine oxazoline derivatives with sulfate groups at the C-6 are effectively oligomerized by the enzyme under weak alkaline conditions, to give alternating 6-sulfated keratan sulfate oligomers in good yields. The enzyme also recognized N-acetyllactosamine oxazoline derivatives with sulfate groups at both the C-6 and the C-6', which provides fully 6-sulfated KS oligomers in good yields under similar conditions. Nonsulfated LacNAc oxazoline is difficult to oligomerize enzymatically. The catalysis mechanism of KSase II involves a sugar oxazolinium ion that requires the 6-sulfate group in the GlcNAc residue not only in hydrolysis of keratan sulfate chains, but also in oligomerization of oxazoline monomers
specificity of the transglycosylation. The oxazoline derivative of 6-O-sulfonato-N-acetyllactosamine is processively oligomerized to the corresponding hexamer or longer. This result strongly implies that the enzyme has the large positively numbered subsites. In contrast, the transglycosylation of the su-LacNAc oxazoline donor with the 6-O-sulfonato-Lewis X (su-LeX) acceptor solely gave the su-LacNAc-su-LeX pentasaccharide. In addition, both the oxazoline derivatives of su-LeX and 6,6'-di-O-sulfonato-LacNAc are exclusively oligomerized to the corresponding dimers respectively. These results strongly suggest that the steric hindrance exists around the (+3)(+4) subsites in keratanase II. Furthermore, KSase II-catalyzed reaction of the excess su-LeX oxazoline with the su-LacNAc gives the su-LeX-su-LacNAc pentasaccharide as the sole transglycosylation product, also implying the steric hindrance at the catalytic center hampering processive shift of this pentasaccharide. Thus, KSase II has the sterically crowded structures at the catalytic center and around the (+3)(+4) subsites, which are all expected to be tunnel-like
the enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Gal-beta-(1->4)-[Fuc-alpha-(1->3)]-GlcNAc(6-OSO3-)) (su-Lex) soxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields. Exclusive formation of the beta-(1->3) glycosidic bond
specificity of the transglycosylation. The oxazoline derivative of 6-O-sulfonato-N-acetyllactosamine is processively oligomerized to the corresponding hexamer or longer. This result strongly implies that the enzyme has the large positively numbered subsites. In contrast, the transglycosylation of the su-LacNAc oxazoline donor with the 6-O-sulfonato-Lewis X (su-LeX) acceptor solely gave the su-LacNAc-su-LeX pentasaccharide. In addition, both the oxazoline derivatives of su-LeX and 6,6'-di-O-sulfonato-LacNAc are exclusively oligomerized to the corresponding dimers respectively. These results strongly suggest that the steric hindrance exists around the (+3)(+4) subsites in keratanase II. Furthermore, KSase II-catalyzed reaction of the excess su-LeX oxazoline with the su-LacNAc gives the su-LeX-su-LacNAc pentasaccharide as the sole transglycosylation product, also implying the steric hindrance at the catalytic center hampering processive shift of this pentasaccharide. Thus, KSase II has the sterically crowded structures at the catalytic center and around the (+3)(+4) subsites, which are all expected to be tunnel-like
the enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Gal-beta-(1->4)-[Fuc-alpha-(1->3)]-GlcNAc(6-OSO3-)) (su-Lex) soxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields. Exclusive formation of the beta-(1->3) glycosidic bond
the enzyme does not catalyze the hydrolysis of phenyl beta-D-galactoside. beta-D-Gal-(1->3)-2-acetamido-2-deoxy-beta-D-Glc-(1->3)-beta-D-Gal-(1->4)-D-Glc is completely refractory to the action of this enzyme
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DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Carcinoma, Papillary
Simultaneous expression of keratan sulphate epitope (a sulphated poly-N-acetyllactosamine) and blood group ABH antigens in papillary carcinomas of the human thyroid gland.
Simultaneous expression of keratan sulphate epitope (a sulphated poly-N-acetyllactosamine) and blood group ABH antigens in papillary carcinomas of the human thyroid gland.
expression of a C-terminally truncated, recombinant keratanase-II in Escherichia coli. The truncated enzyme is designed to remove the domains predicted to be unnecessary for catalytic activity and detrimental to recombinant expression in Escherichia coli
synthetic truncated keratanase II gene is subcloned into the NdeI and XhoI sites of pET30a, resulting in the expression construct pKSII, which placed a His6 tag at the extreme C-terminus of the enzyme, expression in Escherichia coli BL21
an LC-MS/MS assay utilising keratan sulphate disaccharides derived from keratanase-II digestion provides a sensitive and specific means for quantitation of urinary keratan sulfate, a screening biomarker for Morquio A. The C-terminally truncated, recombinant keratanase-II meets all performance requirements and can be produced in a rapid and reproducible manner
sulfated type 2 carbohydrate chains are known tumor-associated carbohydrate antigens (TACAs). The enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Galbeta(1->4)[Fucalpha(1->3)]GlcNAc(6-OSO3-)) oxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields
sulfated type 2 carbohydrate chains are known tumor-associated carbohydrate antigens (TACAs). The enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Galbeta(1->4)[Fucalpha(1->3)]GlcNAc(6-OSO3-)) oxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields
sulfated type 2 carbohydrate chains are known tumor-associated carbohydrate antigens (TACAs). The enzyme efficiently catalyzes the transglycosylation reaction of the sulfated Lewis X (Galbeta(1->4)[Fucalpha(1->3)]GlcNAc(6-OSO3-)) oxazoline derivative, thereby giving the su-Lex dimer as the main product in good yields
Yamazaki, Y.; Sezukuri, K.; Takada, J.; Kimura, S.; Ohmae, M.
A novel chemoenzymatic synthesis of sulfated type 2 tumor-associated carbohydrate antigens by transglycosylation of sulfated Lewis X oxazoline catalyzed by keratanase II
Ohmae, M.; Sakaguchi, K.; Kaneto, T.; Fujikawa, S.; Kobayashi, S.
Keratanase II-catalyzed synthesis of keratan sulfate oligomers by using sugar oxazolines as transition-state analogue substrate monomers a novel insight into the enzymatic catalysis mechanism
Recombinant, truncated B. circulans keratanase-II Description and characterisation of a novel enzyme for use in measuring urinary keratan sulphate levels via LC-MS/MS in Morquio A syndrome