Characterization of the cysteine residues in MG2 and identification of heterotypic complexes involving MG2 and SIgA by peptide display
Date
2002
DOI
Authors
Soares, Rodrigo Villamarim
Version
OA Version
Citation
Abstract
1. CHARACTERIZATION OF THE CYSTEINE RESIDUES IN MG2: Human salivary mucin MG2 is a 180 kDa glycoprotein secreted by
submandibular/sublingual and minor salivary glands. Secreted MG2 contains
a domain with the only two cysteines (Cys45 and Cys50) in the polypeptide
backbone and it has been shown that this domain in native and recombinant
MG2 is involved in mucin binding to oral microbes.
Since reduction and alkylation of MG2 was shown to abolish binding to
oral microbes, the present study was undertaken to determine whether the
cysteine residues exist in the dithiol or disulfide form. Electrophoretic
analyses under reducing and non-reducing conditions showed that
intermolecular disulfide bonds do not occur between MG2 molecules. The
same incorporation of radiolabeled iodoacetamide into MG2 was obtained
with or without prior reduction. When radiolabeled alkylated MG2 was
digested with Endoproteinase LysC and the derived peptides were separated
by reversed phase high performance liquid chromatography, radioactivity was
found in two fractions. Mass spectral analyses of these fractions showed the
presence of peptide 1 (Cys-Leu-His-Lys-) and peptide 2 (Arg-Cys-Arg-Pro-),
both containing carboxymethylated cysteines.
These results show that the cysteines in the structural motif associated
with bacterial binding exist in the dithiol form and suggest the potential use of
cysteine-containing peptides as agents to modify interactions of MG2 with
microbes and oral surfaces. [TRUNCATED]
Description
Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 2002 (Periodontology and Oral Biology).
Includes bibliographical references (leaves 127-152).
Includes bibliographical references (leaves 127-152).
License
This work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.