Use of Photoaffinity Labeling and Site-directed Mutagenesis for Identification of the Key Residue Responsible for Extraordinarily High Affinity Binding of UCN-01 in Human α1-Acid Glycoprotein

Abstract

7-Hydroxystaurosporine (UCN-01

A Site-Directed Mutagenesis Study of Drug-Binding Selectivity in Genetic Variants of Human α1-Acid Glycoprotein

“…In addition to this region, amino acid residues in the regions surrounding positions 25 and 160 are also involved in drug binding to AGP. Previously, we observed that UCN‐01 has the greatest binding affinity for AGP, and does not selectively bind to AGP variants 14. This observation suggests that amino acid residues located near W160 that significantly contribute to UCN‐01 binding may not play an important role in drug‐binding selectivity.…”

“…Using a photoaffinity labeling, we found that residues in the Y91‐R105 range of the F1*S variant are involved in flunitrazepam binding 12. In addition, W25 and W160 play important roles in the binding of progesterone and UCN‐01, respectively 13, 14. Recently, Zsila and Iwao15 also found that W25 is involved in drug binding to AGP based on induced circular dichroism spectra.…”

“…To study the drug‐binding characteristics of the F1*S variant, we previously constructed an expression system for a recombinant F1*S variant in Pichia pastoris (GS115 strain)17 and using this expression system, identify the amino acid residues that are directly involved in drug binding to AGP 14…”

Structural Insights into Differences in Drug-binding Selectivity between Two Forms of Human α1-Acid Glycoprotein Genetic Variants, the A and F1*S Forms

“…Attempts to map the amino acids involved in drug binding of hAGP have been made using a range of different experimental approaches, including fluorescent probe displacement (12), chemical modification (13,14), photoaffinity labeling (15,16), and other spectroscopic methods (17). However, most of these investigations used mixtures of hAGP variants, resulting in some contradictory results.…”

Subdomain IIIA of Dog Albumin Contains a Binding Site Similar to Site II of Human Albumin

“…We reported that dog albumin is suitable for investigating drug-drug interactions on site II, whereas rat, rabbit, and bovine albumins are suitable for examining the binding of site I drugs (Kosa et al, 1997). Based on that study we attempted to elucidate the structural configuration of the binding site of dog albumin that resembles site II of HSA, using a photoaffinity labeling method (Garabedian and Yount, 1991;Chuang et al, 1999;DeSantis et al, 2000;Katsuki et al, 2005).…”