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Purification and characterization of subunits of a high molecular weight human salivary mucin
S Kawagishi1, R E Fahim, K H Wong
1Department of Biochemistry, University of Toronto, Ontario, Canada.
Abstract:
A high molecular-weight mucin was purified from human submandibular-sublingual saliva. The purity of the mucin preparation was demonstrated by the absence of other salivary proteins, by antibody reactivity and by gel electrophoresis. After reduction with mercaptoethanol a putative link component with approximate Mr 150,000 and a glycoprotein component of higher Mr could be detected by gel electrophoresis. These subunits were subsequently purified and they showed distinct differences in their amino acid compositions, demonstrating that the mucin consisted of two different subunits. The link had a number of similarities with the link component of intestinal mucin and a parotid agglutinin and has previously been shown to cross-react with antiserum to link component from intestinal mucin. Salivary and intestinal mucins may therefore have similar subunit structure.
Insights
High molecular-weight mucin from human saliva was purified and found to consist of two distinct subunits. This finding suggests a similar subunit structure between salivary and intestinal mucins.
Area of Science:
- Biochemistry
- Molecular Biology
- Salivary Gland Research
Background:
- Human saliva contains high molecular-weight mucins crucial for oral health.
- Understanding mucin structure is key to elucidating their protective functions.
- Previous studies suggested potential structural similarities between different types of mucins.
Purpose of the Study:
- To purify and characterize the high molecular-weight mucin from human submandibular-sublingual saliva.
- To determine the subunit composition of this salivary mucin.
- To compare its structure with other known mucins, such as intestinal mucin.
Main Methods:
- Purification of high molecular-weight mucin from human submandibular-sublingual saliva.
- Assessment of purity using gel electrophoresis and antibody reactivity.
- Analysis of subunits after reduction with mercaptoethanol.
- Amino acid composition analysis of purified subunits.
Main Results:
- A high molecular-weight mucin was successfully purified from human saliva.
- Gel electrophoresis revealed two distinct subunits after reduction: a link component (approx. Mr 150,000) and a higher Mr glycoprotein component.
- Amino acid analysis confirmed these subunits possess different compositions.
- The link component exhibited similarities to the link component of intestinal mucin.
Conclusions:
- Human submandibular-sublingual salivary mucin is composed of at least two distinct subunits.
- The structural similarities suggest a conserved subunit organization across salivary and intestinal mucins.
- This research contributes to understanding mucin heterogeneity and evolution.