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proteins, the calculation of the curvature uctuations might prove a useful tool in the
search of protein-like sequences. Preliminary results on more rened minimalistic
models [31] completely conrm the scenario presented here.
6.4. Concluding Remarks
The scientic community studying protein folding has proposed a large number of
competitive models many of which are capable of reproducing, albeit at a qualitative
level, the main thermodynamic features of the process. A comparative study of the
kinetic, geometric and topological properties of the energy landscape is therefore
mandatory in order to spot which of them are weak and model dependent and
which are instead generalized features of any systems characterized by a rough and
funnelled energy landscape. Needless to say, the latter are likely to be shared by
real proteins, too.
The two approaches described here appear as complementary. Topological and
global geometrical features of the energy landscape seem to contain a lot of informa-
tion on the folding propensity of given amino acidic sequences, at least as minimal
models are considered. These approaches are however in their infancy so that fur-
ther investigation along these lines will be necessary to devise eective methods
able to elucidate the nature of the energy landscape of protein-like heteropolymers.
Acknowledgments
We would like to thank all the colleagues in collaboration with whom the results
discussed here have been obtained and especially M. Baiesi, R. Franzosi, R. Livi,
L. N. Mazzoni, A. Politi, L. Tattini and A. Torcini. We also acknowledge useful
discussions with R. Burioni and D. Cassi. This work is part of the EC (FP6-
NEST) project Emergent organisation in complex biomolecular systems (EMBIO)
(EC contract n. 012835) whose nancial support is acknowledged.
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