Amidase and peptidase activities of polyclonal immunoglobulin G present in the sera of patients with rheumatoid arthritis |
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Authors: | Kinji Matsuura Shinya Ikoma Masafumi Sugiyama Masanori Funauchi Hyogo Sinohara |
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Institution: | (1) Department of Biochemistry, Kinki University School of Medicine, Osaka-Sayama, 589-8511 Osaka, Japan;(2) Department of Internal Medicine, Kinki University School of Medicine, Osaka-Sayama, 589-8511 Osaka, Japan;(3) Life Science Institute, Kinki University School of Medicine, Osaka-Sayama, 589-8511 Osaka, Japan;(4) Present address: Medical School, Department of Pathology and Laboratory Medicine, The University of Texas Houston, 77225 Houston, TX |
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Abstract: | Polyclonal Immunoglobulin (Ig) G from patients with rheumatoid arthritis (RA) and healthy subjects hydrolyzed carbobenzoxy−Val−Gly−Arg
p-nitroanilide and D−Pro−Phe−Arg p-nitroanilide. RA IgG exhibited higher activity against the former substrate, but not the latter. On the other hand, RA IgG
showed reduced activity against D−Pro−Phe−Arg methylcoumarinamide, when compared with those of the healthy controls. These
results suggest that RA IgGs differ from normal IgGs in the substrate specificity of amidase activity. Preliminary studies
have shown that two out of three RA IgG samples cleaved a pentapeptide—Gln−Arg−Arg−Arg−Ala−Ala— which is assumed to be associated
with the risk of developing RA (Gregersen, P. K. et al. (1987), Arthritis Rheum.
30, 1205–1213). By contrast, virtually no cleavage of the same peptide was observed with IgG from healthy controls. A peptide
analog, Gln−Arg−Arg−Trp−Ala, was not cleaved at all by any IgGs examined either from RA patients or healthy controls. |
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Keywords: | Amidase activity of IgG peptidase activity of IgG rheumatoid arthritis shared epitope |
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