Proteolysis activity of IgM antibodies from rheumatoid arthritis patients' sera: evidence of atypical catalytic site
✍ Scribed by A. S. Kamalanathan; C. Goulvestre; B. Weill; M. A. Vijayalakshmi
- Book ID
- 102372883
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 229 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0952-3499
- DOI
- 10.1002/jmr.1035
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✦ Synopsis
Abstract
The IgM antibodies from rheumatoid arthritis (RA) patients' sera were screened for peptide hydrolyzing activity. Recovery of structurally intact IgM antibodies (Abs), in a single step, was achieved using a weak anion‐exchange methacrylate monolith disk. The IgM Abs from patients' sera hydrolyzed the Pro‐Phe‐Arg‐4‐methyl‐coumaryl‐7‐amide (PFR‐MCA) substrate appreciably compared to the healthy donors. The apparent K~m~ values of IgM Abs from patients' sera were between 0.4 and 0.7 mM. Furthermore, IgM Abs displayed 5 to 10‐folds greater proteolysis activity than IgG Abs, recovered from the same pathological serum. The proteolysis activity, as a function, was found to be independent of IgM‐RF titer value. Affinity labeling approach targeted at the catalytic site histidine was studied, using a specific irreversible inhibitor, N‐α‐tosyl‐L‐lysine chloromethyl ketone (TLCK). Despite modification of catalytic His, observation of serine protease like activity suggest presence of an atypical catalytic framework in a few pathological IgM Abs. Copyright © 2010 John Wiley & Sons, Ltd.