Amino acid resolution of halothane binding sites in serum albumin.
Saturable binding of various inhaled anesthetics to serum albumin has been shown with a variety of approaches. In order to determine the location of halothane binding sites in serum albumin, both human and bovine serum albumins (HSA and BSA) were photolabeled with [14C]halothane, and subjected to proteolysis and microsequencing. BSA was found to have a higher affinity for halothane than HSA, and it contained two specifically labeled sites. One site was characterized by diffuse labeling from Trp212-Leu217, and the other by a more discrete and higher affinity labeling at Trp134-Gly135. HSA contained only a single labeled site, and although lower affinity, was determined to be analogous to BSA Trp212. The position 130-140 region of HSA, having a leucine instead of tryptophan at position 134, was not labeled. These results demonstrate specific and discrete binding of an inhaled anesthetic to a mammalian-soluble protein, and further suggest the importance of aromatic residues as one feature of inhaled anesthetic binding sites.
Eckenhoff
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Departments of Anesthesia and Physiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-4283, USA.
D000345:Affinity Labels; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003488:Cyanogen Bromide; D006221:Halothane / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000378:metabolism
D000345:Affinity Labels; D010446:Peptide Fragments; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D003488:Cyanogen Bromide; D006221:Halothane