Hydrogen-Deuterium exchange kinetics in beta-lactoglobulin (-)-epicatechin complexes studied by FTIR spectroscopy

作者：Caporaletti Francesca; Carbonaro Marina; Maselli Paola; Nucara Alessandro^*

来源：International Journal of Biological Macromolecules, 2017, 104: 521-526.

DOI：10.1016/j.ijbiomac.2017.06.028

• beta-Lactoglobulin
• Amide I
• Isotopic exchange
• (-)-Epicatechin
• FTIR

Hydrogen-Deuterium exchange kinetics of beta-lactoglobulin and p-lactoglobulin (-)-epicatechin solutions has been investigated through the analysis of the amide I absorption band at 1650 cm(-1) in the FTIR spectrum. H-D substitution in NH amides and residues of the protein results in a slight red-shift and in intensity changes of the amide I components: either these effects have been inspected in the framework of the Principal Components Analysis methods. The present analysis allowed to unveil three H-D kinetics at the timescale of the oligomeric fluctuations of the protein. A fast mechanism (lifetime from 5 to 10 min) can be ascribed to the dynamics of protein oligomers and aggregates at the scale of the quaternary structure variations, and it is not observed in the complexes,beta-lactoglobulin (-)-epicatechin. The other slowest kinetics, whose lifetimes are in the range 1-10h, are here associated to dynamics of high-molecular weight complexes that hamper the proton exchange. The role of (-)-epicatechin as an enhancer of the formation of stable high-molecular weight aggregates from beta-lactoglobulin is also discussed by comparison of the lifetimes at different protein concentrations.

• 出版日期2017-11