Structural basis of binding of fluorescent, site-specific dansylated amino acids to human serum albumin

Abstract

Human serum albumin (HSA) has two primary binding sites for drug molecules. These sites selectively bind different dansylated amino acid compounds, which—due to their intrinsic fluorescence—have long been used as specific markers for the drug pockets on HSA. We present here the co-crystal structures of HSA in complex with six dansylated amino acids that are specific for either drug site 1 (dansyl-l-asparagine, dansyl-l-arginine, dansyl-l-glutamate) or drug site 2 (dansyl-l-norvaline, dansyl-l-phenylalanine, dansyl-l-sarcosine). Our results explain the structural basis of the site-specificity of different dansylated amino acids. They also show that fatty acid binding has only a modest effect on binding of dansylated amino acids to drug site 1 and identify the location of secondary binding sites.

A fluorescent fatty acid probe, DAUDA, selectively displaces two myristates bound in human serum albumin

“…34 An identical feature in these two structures is that the sulfonyl groups are close to the positively charged residues (Arg218 and Arg222) of rHSA. However, the location of the dansyl group of DAUDA in the current structure is different from the dansyl group in the rHSADanN structure (PDB 2XVV) 34 [ Fig. 1(D)].…”

“…8,9,[30][31][32][33] The binding modes of these dansylated amino acids were largely confirmed by a recent structural study by Curry and coworkers. 34 They showed that ansyl-L-asparagine (DanN), dansyl-L-glutamate (DanE) and dansyl-L-arginine (DanR) with polar or charged amino acid binds to FA7 (Sudlow site I), while dansyl-L-phenylalanine (DanF), dansyl-L-norvaline (DanNV) and dansylsarcosine (DanSRC) with hydrophobic amino acid are specific for FA3/4 (Sudlow site II). 34 An identical feature in these two structures is that the sulfonyl groups are close to the positively charged residues (Arg218 and Arg222) of rHSA.…”

“…34 They showed that ansyl-L-asparagine (DanN), dansyl-L-glutamate (DanE) and dansyl-L-arginine (DanR) with polar or charged amino acid binds to FA7 (Sudlow site I), while dansyl-L-phenylalanine (DanF), dansyl-L-norvaline (DanNV) and dansylsarcosine (DanSRC) with hydrophobic amino acid are specific for FA3/4 (Sudlow site II). 34 An identical feature in these two structures is that the sulfonyl groups are close to the positively charged residues (Arg218 and Arg222) of rHSA. However, the location of the dansyl group of DAUDA in the current structure is different from the dansyl group in the rHSADanN structure (PDB 2XVV) 34 [ Fig.…”

Drug likeness prediction of 5-hydroxy-substituted coumarins with high affinity to 5-HT1A and 5-HT2A receptors

“…According to crystallographic studies ligands such as fatty acids can bind up to seven sites in HSA including both Sudlow´s sites (Carter and Xo, 1994). Site 1 is a large, flexible and multi-chamber cavity within the core of subdomain IIA that comprises all six helices of the subdomain and additional residues from subdomains IB, IIB and IIIA (Ryan et al, 2011). Site 2 in subdomain IIIA is smaller than site 1, and is a largely apolar cavity with well-defined polar features.…”

Human Serum Albumin Binding of 2-[(Carboxymethyl)sulfanyl]-4-oxo-4-(4-tert-butylphenyl)butanoic Acid and its Mono-Me Ester

“…One carboxylate makes the salt bridge with Lys199, the second carboxylate is in close vicinity of Arg's 218 and 222 [39]; 2XVW -Dansyl-L-arginine bound to Sudlow site I [39]. The guanidino moiety of the ligand makes the salt bridge with the Glu153, carboxylate of the ligand is in the close vicinity of Arg218.…”