Interaction of pirprofen enantiomers with human serum albumin.
The interaction of pirprofen enantiomers with human serum albumin (HSA) was investigated by means of high-performance liquid chromatography (HPLC), circular dichroism (CD), and 1H NMR spectroscopy. HPLC experiments indicated that both pirprofen enantiomers were bound to one class of high-affinity binding sites (n(+) = 1.91 +/- 0.13, K(+) = (4.09 +/- 0.64) x 10(5) M-1, n(-) = 2.07 +/- 0.13, K(-) = (6.56 +/- 1.35) x 10(5) M-1) together with nonspecific binding (n'K'(+) = (1.51 +/- 0.21) x 10(4) M-1, n'K'(-) = (0.88 +/- 0.13) x 10(-4) M-1). Slight stereoselectivity in specific binding was demonstrated by the difference in product n(+)K(+) = (0.77 +/- 0.08) x 10(6) M-1 vs. n(-)K(-) = (1.30 +/- 0.21) x 10(6) M-1, i.e., the ratio n(-)K(-)/n(+)K(+) = 1.7. CD measurements showed changes in the binding sites located on the aromatic amino acid side chains (a small positive band at 315 nm and a pronounced negative extrinsic Cotton effect in the region 250-280 nm). The protein remains, however, in its predominantly alpha-helical conformation. The 1H NMR difference spectra confirmed that both pirprofen enantiomers interacted with HSA specifically, most probably with site II on the albumin molecule.
Oravcová
J
J
Institute of Experimental Pharmacology, Slovak Academy of Sciences, Bratislava.
Mlynárik
V
V
Bystrický
S
S
Soltés
L
L
Szalay
P
P
Bohácik
L
L
Trnovec
T
T
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010666:Phenylpropionates / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism*; D013237:Stereoisomerism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D010666:Phenylpropionates; D012709:Serum Albumin; C008924:pirprofen