title: Partial characterisation of high-molecular weight glycoconjugates in the trail mucus of the freshwater pond snail Lymnaea stagnalis.
abstract: We have studied the glycoconjugates in trail mucus of the pond snail Lymnaea stagnalis. The mucus was dissolved with 6 M guanidinium hydrochloride (GuHCl) and the major component was comprised of very high-M(r) glycoconjugates that were eluted in the void volume of a Sepharose CL-4B gel-filtration column. This high-M(r) material was pooled and thereafter subjected to density gradient centrifugation first in 4 M GuHCl/CsCl and subsequently 0.2 M GuHCl/CsCl to further remove non-glycosylated proteins and DNA. The harvested glycoconjugate pool chromatographed in the void volume of Sepharose CL-2B. However, reduction of disulfide bonds lowered the molecular size of approximately 80% of the void material yielding a major fragment and some minor smaller fragments in gel chromatography. The reduced glycoconjugates were digested with papain and yielded high molecular weight, proteinase-resistant glycopeptides. This fragmentation pattern is similar to that found for oligomeric gel-forming mucins in mammals and the amino acid composition (60% Ser/Thr) and sugar analysis of the glycopeptides is consistent with mucin-like molecules, there being no significant amounts of xylose or uronic acids. The residual 20% of the preparation, which apparently resisted reduction and protease digestion, had a similar amino acid composition to the bulk, but was somewhat different in sugar composition, containing some xylose and a significant amount of glucuronic acid. The two groups of molecules had very different morphologies in the electron microscope. Taken together, these data suggest that trail mucus is a complex mixture of at least two families of protein-glycoconjugate molecules based upon the gel-forming mucin and proteoglycan families, though we cannot rule out that polysaccharides may also be present.
authors.affiliation: School of Biological Sciences, University of Manchester, Manchester M13 9PL, UK. simon.ballance@biotech.ntnu.no
authors.forename: Simon
authors.initials: S
authors.lastname: Ballance
authors.forename: Marj
authors.initials: M
authors.lastname: Howard
authors.forename: Keith N
authors.initials: KN
authors.lastname: White
authors.forename: Catherine R
authors.initials: CR
authors.lastname: McCrohan
authors.forename: David J
authors.initials: DJ
authors.lastname: Thornton
authors.forename: John K
authors.initials: JK
authors.lastname: Sheehan
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D002241:Carbohydrates / Q000737:chemistry; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D005618:Fresh Water; D020723:Glucuronic Acid / Q000737:chemistry; D006001:Glycoconjugates / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D006020:Glycopeptides / Q000737:chemistry; D008195:Lymnaea / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D009093:Mucus / Q000737:chemistry* / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D013329:Structure-Activity Relationship; D014994:Xylose / Q000737:chemistry
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D006001:Glycoconjugates; D006020:Glycopeptides; D020723:Glucuronic Acid; D014994:Xylose; D010447:Peptide Hydrolases