Formation of complexes between PAMAM-NH2 G4 dendrimer and L-α-tryptophan and L-α-tyrosine in water.
Interactions between electromagnetic radiation and the side substituents of aromatic amino acids are widely used in the biochemical studies on proteins and their interactions with ligand molecules. That is why the aim of our study was to characterize the formation of complexes between PAMAM-NH2 G4 dendrimer and L-α-tryptophan and L-α-tyrosine in water. The number of L-α-tryptophan and L-α-tyrosine molecules attached to the macromolecule of PAMAM-NH2 G4 dendrimer and the formation constants of the supramolecular complexes formed have been determined. The macromolecule of PAMAM-NH2 G4 can reversibly attach about 25 L-α-tryptophan molecules with equilibrium constant K equal to 130±30 and 24±6 L-α-tyrosine molecules. This characterization was deduced on the basis of the solubility measurements of the amino acids in aqueous dendrimer solutions, the (1)H NMR and 2D-NOESY measurements of the dendrimer solutions with the amino acids, the equilibrium dialysis and the circular dichroism measurements of the dendrimer aqueous solutions with L-α-tryptophan. Our date confirmed the interactions of L-α-tryptophan and L-α-tyrosine with the dendrimer in aqueous solution and indicated a reversible character of the formed complexes.
Department of Physical Chemistry, University of Lodz, Pomorska 165, 90-236 Lodz, Poland. Electronic address: adam.buczkowski@chemia.uni.lodz.pl.
Adam
A
Buczkowski
Department of Inorganic and Analytical Chemistry, University of Lodz, Tamka 12, 91-403 Lodz, Poland.
Pawel
P
Urbaniak
Department of Physical Chemistry, University of Lodz, Pomorska 165, 90-236 Lodz, Poland.
Sylwia
S
Belica
Department of General Biophysics, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
Szymon
S
Sekowski
Department of General Biophysics, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
Maria
M
Bryszewska
Department of Physical Chemistry, University of Lodz, Pomorska 165, 90-236 Lodz, Poland. Electronic address: paleczb@uni.lodz.pl.
Bartlomiej
B
Palecz
D050091:Dendrimers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D014364:Tryptophan / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D050091:Dendrimers; C104700:PAMAM Starburst; D014867:Water; D014443:Tyrosine; D014364:Tryptophan
(1)H NMR and NOESY spectroscopy; Circular dichroism; Equilibrium dialysis; PAMAM G4 dendrimer; l-α-tryptophan; l-α-tyrosine