| Proteins are essential for living systems. Whilst functioning, they absorb and release energy. As proteins can only function in narrow temperature ranges, excess energy has to be removed efficiently. Understanding energy transport in proteins has started to develop for proteins in solution. However, about 50 % of the cellular proteins are embedded in membranes. Little is known about the energy flow in membrane proteins; the effect of the membrane on the energy transport and vice versa have remained unexplored. Here we aim at understanding the molecular mechanism of energy transport in transmembrane proteins. We will elucidate the mechanisms of energy transfer by directly watching the energy flow in a model peptide embedded in a membrane-like environment (lipid vesicles and bilayers) using ultrafast spectroscopic techniques. A set of model peptide helices will be used with a chromophore attached at one end. Excitation of the chromophore with a femtosecond laser pulse will result in a large local temperature increase. The subsequent transfer of the excess energy along the helix will be monitored by interrogating the temperature at different molecular groups of the peptide with a second, non-perturbing laser pulse. Thereby these molecular groups act as local thermometers. We will also study the subsequent energy transfer out of the peptide into the lipid layer (through local thermometers present in the lipids), and finally into the surrounding water molecules. With state-of-the-art 2D spectroscopic techniques the structure of the lipid layer during the energy transport will be detected. The ultimate goal is to understand why transport and storage of energy in nature are so efficient. |
