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Subunit structure of porcine submaxillary mucin
1Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio 44106.
Biochemistry
|July 11, 1989
Summary
This study reveals the complex structure of porcine submaxillary mucin, detailing its subunits, glycosylated domains, and associated proteins. Mucin polydispersity arises from variations in linked unit number and size.
Area of Science:
- Biochemistry
- Glycobiology
- Molecular Biology
Background:
- Porcine submaxillary mucin is a high molecular weight glycoprotein with a complex structure.
- Understanding mucin structure is crucial for elucidating its biological functions in various tissues.
Purpose of the Study:
- To investigate the structural organization of porcine submaxillary mucin using degradative techniques.
- To characterize the molecular weight, composition, and domains of mucin subunits and their fragments.
Main Methods:
- Disulfide bond reduction to release mucin subunits and associated proteins.
- Enzymatic digestion (trypsinization and pronase digestion) to generate smaller fragments.
- Molecular weight determination and amino acid composition analysis.
Main Results:
- Reduction of disulfide linkages yielded mucin subunits (0.5-2.5 x 10^6 Da) and a ~140 kDa associated protein.
- Trypsinization produced glycosylated domains (~270 kDa) with limited amino acid diversity and smaller peptides.
- Pronase digestion of glycosylated domains generated ~17 kDa fragments, suggesting tandem repeat units.
Conclusions:
- Porcine submaxillary mucin exhibits a polydisperse structure due to variable linkage and unit size.
- The glycosylated domains likely comprise variable numbers of 81-amino acid tandem repeats.
- The structural organization is comparable to cervical and intestinal mucins, involving subunits, link proteins, and glycosylated domains.