J. Kuszewski et al., FAST FOLDING OF A PROTOTYPIC POLYPEPTIDE - THE IMMUNOGLOBULIN BINDINGDOMAIN OF STREPTOCOCCAL PROTEIN-G, Protein science, 3(11), 1994, pp. 1945-1952
The folding of the small (56 residues) highly stable B1 immunoglobulin
binding domain (GB1) of streptococcal protein G has been investigated
by quenched-flow deuterium-hydrogen exchange. This system represents
a paradigm for the study of protein folding because it exhibits no com
plicating features superimposed upon the intrinsic properties of the p
olypeptide chain. Collapse to a semicompact state exhibiting partial o
rder, reflected in protection factors for ND-NH exchange up to 10-fold
higher than that expected for a random coil, occurs within the dead t
ime (less than or equal to 1 ms) of the quenched flow apparatus. This
is followed by the formation of the fully native state, as monitored b
y the fractional proton occupancy of 26 backbone amide groups spread t
hroughout the protein, in a single rapid concerted step with a half-li
fe of 5.2 ms at 5 degrees C.