Jp. Laussac et al., 3-DIMENSIONAL STRUCTURE OF AL3-CONTAINING PEPTIDES BY NMR AND MOLECULAR MODELING STUDY - COMPLEXATION OF A THYMIC HORMONE(), Coordination chemistry reviews, 149, 1996, pp. 179-191
The biological coordination chemistry of aluminum has received only li
mited attention until the last decade. To this end, the interaction be
tween aluminum and thymulin, a linear nonapeptide of thymic origin iso
lated from serum, was investigated by using high resolution NMR spectr
oscopy. These experiments were performed in two different solvents, na
mely DMSO-d(6) and the so-called cryoprotective mixture (water+DMSO),
i.e. a mixture that resembles water in many properties. NMR data analy
sis indicates the existence of one type of complex with a 1:2 stoichio
metry, associating two peptide molecules and one Al3+ cation. In this
complex the Asn(9) carboxylate C-terminal group and the Ser(4) hydroxy
l group are ligated to the metal. The three-dimensional structure of t
he 1:2 Al3+-thymulin complex was determined by distance geometry calcu
lations and restrained molecular dynamics simulations. Distance geomet
ry calculations were performed with the Biosym DG II program using the
NOE interproton distances as constraints. Further structural analysis
was carried out by restrained molecular dynamics calculations with th
e Biosym DISCOVER program.