Inhaled anesthetic binding sites in human serum albumin

Previous evidence suggests multiple anesthetic binding sites on human serum albumin, but to date, we have only identified Trp-214 in an interdomain cl eft as contributing to a binding site. We used a combination of site-direct ed mutagenesis, photoaffinity labeling, amide hydrogen exchange, and trypto phan fluorescence spectroscopy to evaluate the importance to binding of a l arge domain III cavity and compare it to binding character of the 214 inter domain cleft. The data show anesthetic binding in this domain III cavity of similar character to the interdomain cleft, but selectivity for different classes of anesthetics exists. Occupancy of these sites stabilizes the nati ve conformation of human serum albumin. The features necessary for binding in the cleft appear to be fairly degenerate, but in addition to hydrophobic ity, there is evidence for the importance of polarity. Finally, myristate i sosterically competes with anesthetic binding in the domain III cavity and allosterically enhances anesthetic binding in the interdomain cleft.