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Figure 4.
Figure 4. Spin relaxation
dynamics of ubiquitin at 30 bar
(open circle) and at 3 kbar (filled
circle). (a)
15
N longitudinal
relaxation rates,
15
N-R1. (b)
15
N
transverse relaxation rates,
15
N-
R2. (c)
1
H-induced
15
N nuclear
Overhauser effect,
15
N{
1
H}-NOE.
(a)--(c) Data are not included for
E24 and G53 (due to severe line-
broadening), for D21 and A28
(due to spectral overlap at
30 bar), for E16 and V26 (due to
spectral overlap at 3 kbar), for I36
(due to signal disappearance at
3 kbar), and for the Pro residues
(P19, P37, P38) with no amide
groups. (d) Order parameters of
N--H vectors, S
2
. (e) Exchange
contribution to
15
N transverse
relaxation rates,
15
N-Rex. Plots in
(d) and (e) were obtained from
the Modelfree analysis
25,26
of the
spin relaxation parameters for
ubiquitin (pH 4.6 at 20 8C) with
the program FAST-Modelfree
26
under the assumption of isotropic
molecular tumbling. The overall
rotational correlation times were
4.7 ns both at 30 bar and at 3 kbar.
Relaxation parameters for resi-
dues 4, 23, 25, 32, 35 and 49 at
30 bar and residues 2, 4, 9, 13, 14,
17, 28, 29, 32, 43 and 54 at 3 kbar
do not show a reasonable fit to the
Modelfree analysis, giving no
data in (d) and (e).
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