Neutral proteinases of human spleen. Purification and criteria for homogeneity of elastase and cathepsin G

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Abstract
Human spleen contained proteinases active against azo-casein at neutral and alkaline pH values. The activity was stimulated by high ionic strength and some detergents. Optimal extraction of the proteinases from the tissue was achieved with 1.0-M-NaCl containing 0.1% Brij 35 and 0.1% trisodium EDTA. The proteinases were efficiently adsorbed to insoluble material in the absence of salt in the initial stages of purification. Two distinct proteinases were separated by chromatography on DEAE-cellulose, an elastase and a chymotrypsin-like enzyme designated cathepsin G. Both enzymes were highly purified by further column chromatography. The MW of the enzymes were estimated by gel chromatography and sodium dodecyl sulfate-gel electrophoresis. Isoelectric focusing and gel electrophoresis showed that both enzymes are cationic proteins that occur in multiple forms.