Fast compaction of alpha-lactalbumin during folding studied by stopped-flow X-ray scattering.
To monitor the fast compaction process during protein folding, we have used a stopped-flow small-angle X-ray scattering technique combined with a two-dimensional charge-coupled device-based X-ray detector that makes it possible to improve the signal-to-noise ratio of data dramatically, and measured the kinetic refolding reaction of alpha-lactalbumin. The results clearly show that the radius of gyration and the overall shape of the kinetic folding intermediate of alpha-lactalbumin are the same as those of the molten globule state observed at equilibrium. Thus, the identity between the kinetic folding intermediate and the equilibrium molten globule state is firmly established. The present results also suggest that the folding intermediate is more hydrated than the native state and that the hydrated water molecules are dehydrated when specific side-chain packing is formed during the change from the molten globule to the native state.
Arai
Munehito
M
Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Japan.
Ito
Kazuki
K
Inobe
Tomonao
T
Nakao
Masaharu
M
Maki
Kosuke
K
Kamagata
Kiyoto
K
Kihara
Hiroshi
H
Amemiya
Yoshiyuki
Y
Kuwajima
Kunihiro
K
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D007700:Kinetics; D007768:Lactalbumin / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation; D012542:Scattering, Radiation; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000378:metabolism; D014965:X-Rays
D012996:Solutions; D014867:Water; D007768:Lactalbumin