Membrane-bound enzymes. III. Protease activity in leucocytes in relation to erythrocyte membranes

Area of Science:

• Biochemistry
• Cell Biology
• Hematology

Background:

• Protease activity has been detected in human and bovine erythrocyte membranes.
• Conventional preparation methods may introduce contaminants, potentially affecting enzyme activity measurements.

Purpose of the Study:

• To investigate the source and characteristics of protease activity in erythrocyte membranes.
• To determine if contaminating leukocytes contribute to the observed protease activity.

Main Methods:

• Erythrocyte membranes were prepared using standard procedures.
• Protease extraction and activation were performed using potassium thiocyanate (KCNS) or ammonium sulfate ((NH4)2SO4).
• Enzyme purification involved polyacrylamide gel electrophoresis with cationic detergents.

Main Results:

• Membrane-associated protease activity was confirmed and the enzyme was extracted and activated.
• Various substrates, including hide powder-azure and soluble proteins, were hydrolyzed.
• An alkaline protease with similar properties was identified in leukocytes.
• Enzyme activity correlated with the presence of white cells in erythrocyte preparations.

Conclusions:

• The protease activity detected in erythrocyte membranes is likely due to contaminating leukocytes.
• Leukocytic proteases share similar properties with the erythrocytic enzyme, supporting this conclusion.
• Standard erythrocyte preparations may require enhanced purification to exclude leukocyte-derived enzymatic activities.