The interaction of dansyl amino acids with bovine serum albumin

Abstract

The interaction of 5-dimethylaminonaphthalene-l-sulfonyl (DNS or dansyl) amino acids with bovine serum albumin (BSA) was investigated by means of fluorescence measurements. Fluorometric titrations revealed that BSA has one high affinity site (binding constant, Ka = 105 -106 M-l), and other sites of lower affinity (K, = 103 -10 4 M-l) for the probes. Static excitation and emission spectra, lifetimes, time resolved emission spectra, and anisotropy data indicated that the bindingis stabilized mainly through fixation by the high affinity binding site. The binding constant significantly decreased with the increase of the spacer distance between the dansyl and anionic groups of the probe molecule. This observation was explained by considering the change of the electrostatic interaction between the anionic group of the probe and a cationic residue in the vicinity of the site.

The effect of the N-B transition of bovine and human serum albumins on the binding sites of fluorescent probes

“…Possible explanations for this could be, (i) the dimethylamino group is buried in a hydrophobic pocket and is exposed to water with more difficulty, for a probe with higher affinity, and (ii) the conformational transition is shifted to lower pH by a local conformational stabilization with probe binding, hence a higher affinity probe shows the effect more clearly. The experimental results strongly suggest that the dansyl group was buried in a hydrophobic crevice [1].…”

“…The preparation of three anionic dansyl probes, dansyl-glycine (DNS-GIy), dansyl-~-alanine (DNS-/~Ala) and dansyl-piperidic acid (DNS-Pip) was described in the previous paper [1]. All were obtained as sodium salts.…”

“…Fluorometric titrations were performed by the method described in the previous paper [1]. The binding parameters were estimated by the Scatchard equation…”

“…In previous work [1] we prepared a series of dansyl amino acid probes in which the hydrophobic dansyl moiety was separated from an anionic charged group by increasing numbers of methylene spacer groups, and studied the interaction behaviour with bovine serum albumin (BSA) by means of static and time resolved fluorescence techniques. It was shown that BSA has one high affinity site for the probes, at which the fluorophore part of the probe molecule is highly immobilized and the binding affinity is very dependent on the spacer length.…”

Characterization of gelatin-surfactant interaction by thickness measurements of foam films

“…Taking into account results of surface tension measurements this region was identified as a region of saturation of the adsorption layer by gelatin-surfactant complexes of the type sometimes called "inverse micelles" [3].…”