Human respiratory mucous glycoproteins.

Area of Science:

• Biochemistry
• Glycobiology
• Respiratory Medicine

Background:

• Human respiratory mucus analysis typically uses expectorated samples, risking contamination.
• Characterizing airway glycoproteins requires pure specimens for accurate biochemical analysis.

Purpose of the Study:

• To biochemically characterize human airway mucous glycoproteins (MGP) using cultured airways.
• To analyze the size heterogeneity and charge characteristics of biosynthetically produced MGP.

Main Methods:

• Cultured human airways were used to biosynthetically label MGP with 3H-glucosamine or 14C-threonine.
• Gel filtration chromatography (Sepharose 2B, Sephacryl S-1000), DEAE chromatography, and preparative isoelectric focusing were employed.
• Enzymatic cleavage was used to analyze oligosaccharide side chains.

Main Results:

• MGP fractionated over a broad size range on Sephacryl S-1000, indicating significant size heterogeneity.
• MGP exhibited uniform, strong acidic charge characteristics, confirmed by DEAE chromatography and isoelectric focusing.
• Enzymatically cleaved oligosaccharide side chains from MGP were similar in size, regardless of MGP size.

Conclusions:

• Human airways release a family of MGP with considerable size variation.
• These MGP possess a consistent, strong acidic charge and uniformly sized side chains.
• This study provides a purer method for MGP analysis, revealing key biochemical properties.