Biomedical Engineering Reference
In-Depth Information
Figure 2.2
Schematic representation of the alternate
13
C-
12
C labelling scheme.
Sources of
13
C and the resultant labelling patterns in proteins for
conventional uniform labelling are
13
C glucose (A) and for alternate
labelling are selectively
13
C-labelled glycerol (B). Nitrogens are uniformly
labelled with
15
N. One-bond couplings are indicated by red lines. Three-
bond
3
J
CaN
couplings are indicated by red arrows. All homonuclear and
heteronuclear couplings are active in uniformly labelled samples. On the
other hand, homonuclear couplings are not present in alternate-labelled
samples, while heteronuclear couplings are still active. 2-
13
C and 1,3-
13
C
glycerol yield complementary
13
C labelling patterns. (C) The H
a
-C
a
region in a
1
H-
13
C HSQC for uniformly
13
C labelled (left) and [2-
13
C]
glycerol labelled (right) Nck SH3.1. (D) Classification of amino acids
based on the
13
C
a
labelling percentage. Group I residues were more than
80 %
13
C
a
labelled with [2-
13
C] glycerol, while Group III residues were
primary
13
C-labelled with [1,3-
13
C] glycerol. Group II residues were
partially labelled in both labelling schemes. (E) Evolution of N
x/y
C
z
single quantum coherences with various degrees of
13
C
a
-labelling in
neighbouring residues. The figure was generated assuming a nitrogen
transverse relaxation rate of 80 ms. The
13
C
a
-labelling rates of
neighbouring residues were assumed to be 0, 20, 60, and 100%. The
heteronuclear couplings,
1
J
CaiNi
and
2
J
CaiNi+1
, were set to 12 and 9 Hz,
respectively. Adapted from refs 41 and 50.
