FOLDING AND STABILITY OF A FIBRONECTIN TYPE-III DOMAIN OF HUMAN TENASCIN

The folding of an isolated fibronectin type III domain of human tenasc in, a large extra-cellular matrix protein, has been characterised. The isolated module, which has no disulphide bonds, can be reversibly unf olded by chemical denaturant and temperature. Equilibrium unfolding, m easured using a number of different probes, fits to a two-state transi tion, with consistent measures of Delta G(D-N)(H2O) Folding and refold ing rate constants have been determined over a range of denaturant con centrations. The refolding kinetics are bi-phasic, and in the transiti on region the slow phase dominates refolding kinetics. Outside the tra nsition region the folding of the fast-folding species fits to a two-s tate model. There is no evidence for significant accumulation of parti ally folded intermediates. (C) 1997 Academic Press Limited.