The loop hypothesis: contribution of early formed specific non-local interactions to the determination of protein folding pathways.

The extremely fast and efficient folding transition (in seconds) of globular proteins led to the search for some unifying principles embedded in the physics of the folding polypeptides. Most of the proposed mechanisms highlight the role of local interactions that stabilize secondary structure elements or a folding nucleus as the starting point of the folding pathways, i.e.

Non-local residue-residue contacts in proteins are more conserved than local ones.

Non-covalent residue-residue contacts drive the folding of proteins and stabilize them. They may be local-i.e.

An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for "double kinetics" experiments: application to fluorescence resonance excitation energy transfer study of protein folding.

The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals.