A urinary pentasaccharide in bovine mannosidosis

Area of Science:

• Biochemistry
• Glycobiology
• Veterinary Medicine

Background:

• Mannosidosis is a lysosomal storage disorder characterized by the accumulation of mannose-rich oligosaccharides.
• Previous studies have identified various oligosaccharides excreted in the urine of patients with mannosidosis.

Purpose of the Study:

• To identify and characterize the low molecular weight carbohydrate material in the urine of an Angus calf diagnosed with mannosidosis.
• To determine the structure of a novel oligosaccharide excreted in the affected calf's urine.

Main Methods:

• Urine samples were analyzed using paper chromatography to detect oligosaccharide fractions.
• The most abundant oligosaccharide was purified using gel chromatography, zone electrophoresis, and preparative paper chromatography.
• Structural elucidation was performed using nuclear magnetic resonance spectroscopy, optical rotation, sugar analysis, methylation analysis, and enzymatic degradation.

Main Results:

• Abnormally high levels of low molecular weight, mannose-rich carbohydrate material were detected in the calf's urine.
• Five distinct oligosaccharide fractions were identified.
• A novel oligosaccharide, alpha-D-Manp-(1 leads to 6)-beta-D-Manp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to 4)-D-GlcNAc, was purified and structurally characterized.

Conclusions:

• The identified oligosaccharide is a unique structure not previously described in the context of mannosidosis.
• This finding expands the known spectrum of carbohydrate structures associated with mannosidosis.
• The characterization provides valuable insights into the specific enzymatic defect in this animal model of mannosidosis.