A new detergent for the solubilization of the vitamin K-dependent carboxylation system from liver microsomes: Comparison with triton X-100

Abstract

A new nondenaturing zwitterion detergent has been used to solubilize the vitamin K-dependent carboxylating system from rat liver microsomes. The optimal conditions for solubilization were 1% 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) and 1 m NaCl while maximum carboxylating activity was achieved with 0.5% CHAPS, 0.75 m NaCl for a microsomal protein concentration varying from 7.5 to 10 mg/ml. Using CHAPS, high levels of carboxylase activity can be found not only in liver microsomes from vitamin K-deficient rats, but also in microsomes prepared from the livers of normal animals, normal animals supplemented with vitamin K 1, or vitamin K-deficient animals supplemented with vitamin K 1, while little if any activity is detected after Triton X-100 solubilization of the microsomes of such livers. Thus, the new zwitterion detergent proves to be more effective and less denaturing in solubilizing the vitamin K-dependent carboxylase from rat liver microsomes than other detergents used in this system.