Sulfobetaine zwitterionic derivative of cholic acid, q.v. Prepn: L. M. Hjelmeland, Proc. Natl. Acad. Sci. USA 77, 6368 (1980); idem, US 4372888 (1983 to U.S. Secy. Health and Human Services); and physical properties: L. M. Hjelmeland et al., Anal. Biochem. 130, 72 (1983). Physical characterization: R. E. Stark et al., J. Phys. Chem. 88, 6063 (1984). Micellar properties: M. A. Partearroyo et al., Biochem. Int. 16, 259 (1988). Solubilization of membrane proteins: A. J. Bitonti et al., Biochemistry 21, 3650 (1982); W. Wouters et al., Eur. J. Pharmacol. 115, 1 (1985); L. Bancells et al., Biochem. Pharmacol. 36, 2539 (1987); of opioid receptors: J. Simon et al., J. Neurochem. 46, 695 (1986).