Purification of granulocyte neutral protease from human blood and rheumatoid synovial fluid

Abstract

The neutral protease activity of human synovial fluid cells, like that of peripheral blood leucocytes, is located in a granule fraction. It can be solubilised by various agents but only 1 M neutral salts do so without inactivation. Salt-solubilised neutral protease has been purified (300 X) from synovial fluid cells; like preparations obtained in the same way (600 X purified) from peripheral blood leucocytes, it has a broad pH profile of activity (pH 7--10.5) and in this, as well as in substrate specificity and sensitivity to activators and inhibitors, it behaves as a serine-histidine type protease similar to elastase (EC 3.4.21.11). The product showed two major components on polyacrylamide gel electrophoresis. Collagenase or chymotrypsin-like activity were not detected.