Stereoselective binding of beta-blockers to purified rat alpha 1-acid glycoprotein.
The stereoselectivity of binding of four beta-blockers, pindolol, propranolol, oxprenolol and acebutolol, to purified rat alpha 1-acid glycoprotein (AAG) was examined using equilibrium dialysis. Pindolol and propranolol were bound stereoselectively to AAG, whereas binding of oxprenolol was non-stereospecific. Neither of the enantiomers of acebutolol bound to either AAG or any other plasma protein. The affinity of (+)-pindolol was 25 times that of (-)-pindolol, as determined in a single enantiomer experiment. Both enantiomers of propranolol demonstrated two classes of binding sites in AAG, the total binding for the high affinity site for (+)-propranolol being double that of (-)-propranolol, which could explain the higher binding of the (+)-enantiomer in racemate experiments. These results further showed that stereoselective binding to a rat AAG is not a property common to all beta-blockers.
Murai-Kushiya
M
M
National Institute of Hygienic Sciences, Osaka Branch, Japan.
Okada
S
S
Kimura
T
T
Hasegawa
R
R
D000070:Acebutolol / Q000097:blood; D000319:Adrenergic beta-Antagonists / Q000097:blood*; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D003956:Dialysis; D008297:Male; D009961:Orosomucoid / Q000378:metabolism*; D010869:Pindolol / Q000097:blood; D011433:Propranolol / Q000097:blood; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D013237:Stereoisomerism
D000319:Adrenergic beta-Antagonists; D001798:Blood Proteins; D009961:Orosomucoid; D000070:Acebutolol; D011433:Propranolol; D010869:Pindolol