The detection, quantification and partial characterisation of cathepsin B-like activity in human pathological synovial fluids.
In this study, the levels of the cysteine proteinase--cathepsin B were measured in diseased synovial fluids using a steady state fluorometric assay. Cathepsin B-like activity was shown to be present in all the samples analysed, with the rheumatoid arthritic synovial fluids possessing significantly higher concentrations (mean value ca. 416 mg/l) than the osteoarthritic fluids (mean value ca. 142.4 mg/l). In addition, upon treatment with pepsin, all of the rheumatoid arthritis samples were shown to possess additional cathepsin B-like activity, suggesting the presence of a reservoir of latent precursor molecules. By utilising a recently developed biotinylated affinity label for cathepsin B-like proteinases and sheep anti-(human cathepsin B) antibodies, used in combination with SDS-PAGE and Western blotting, the rheumatoid arthritic synovial cathepsin B was shown to exist in two forms with apparent molecular masses of M(r) 29,000 and 42,000. We propose that the former is a functionally active proteinase, whereas the latter is a pepsin activatable proform which, when cleaved by this aspartyl proteinase, is converted into a catalytically competent species of M(r) 20,000.
Duffy
J M
JM
Queen's University of Belfast, Department of Orthopaedic Surgery, Musgrave Park Hospital, Northern Ireland.
Walker
B
B
Guthrie
D
D
Grimshaw
J
J
McNally
G
G
Grimshaw
J T
JT
Spedding
P L
PL
Mollan
R A
RA
D000345:Affinity Labels; D001172:Arthritis, Rheumatoid / Q000201:enzymology*; D015153:Blotting, Western; D002401:Cathepsin B / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006801:Humans; D008970:Molecular Weight; D010003:Osteoarthritis / Q000201:enzymology*; D010434:Pepsin A / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013582:Synovial Fluid / Q000201:enzymology*
D000345:Affinity Labels; D002401:Cathepsin B; D010434:Pepsin A