A rapid method for preparing insect microsomes

1. 1. The 1000 g supernatant of a tissue homogenate is layered on top of a small (< 5 ml) sucrose density gradient and centrifuged for 20 min at very high centrifugal forces in a vertical rotor. 2. 2. Microsomes can be recovered rapidly in suspended form from the middle of the gradient, well separated from mitochondria and soluble (cytosolic) components. 3. 3. Applications to cockroach midgut microsomes and mosquito abdominal tissue microsomes are described, and the method is compared to the classical differential centrifugation method. 4. 4. Cytochrome P-450 monooxygenase activities can be measured on microsomes prepared from midgut tissue of 2-3 Diploptera punctata using this method.