Biomedical Engineering Reference
In-Depth Information
Table 2.4
Characterization of storage protein types from wheat, rye,
barley, and oats [
61,
63
]
Partial amino acid
composition
(mol-%)
b
Q
Repetitive unit
b,c
(frequency)
Group/type
Code
Residues
State
a
P
F + Y
G
L
V
HMW group
HMW-GS x
Q6R2V1
815
a
QQPGQG (72×)
36 13
5.8
20
4.4
1.7
HMW-GS y
Q52JL3
637
a
QQPGQG (50×)
32 11
5.5
18
3.8
2.3
HMW-secalin x Q94IK6
760
a
QQPGQG (66×)
34 15
6.7
20
3.7
1.5
HMW-secalin y Q94IL4
716
a
QQPGQG (60×)
34 12
5.0
18
3.2
1.8
D-hordein
Q40054
686
a
QQPGQG (26×)
26 11
5.5
16
4.1
4.1
MMW group
w 5-gliadin
Q402I5
420
m
(Q)QQQFP (65×)
53 20
10.0
0.7
3.1
0.2
w 1,2-gliadin
Q6DLC7
373
m
(QP)QQPFP (42×)
42 29
9.9
0.8
4.0
0.5
w -secalin
O04365
338
m
(Q)QPQQPFP (32×)
40 29
8.6
0.6
4.4
1.8
C-hordein
Q40055
328
m
(Q)QPQQPFP (36×)
37 29
9.4
0.6
8.6
0.3
LMW group
a /ß-gliadin
Q9M4M5
273
m
QPQPFPPQQPYP
(5×)
36 15
7.4
2.6
8.1
5.1
g -gliadin
Q94G91
308
m
(Q)QPQQPFP (15×)
36 18
5.2
2.9
7.2
4.6
LMW-GS
Q52NZ4
282
a
(Q)QQPPFS (11×)
32 13
5.7
3.2
8.2
5.3
g -40 k-secalin
d
-
-
m
QPQQPFP
34 18
5.5
2.4
7.4
4.7
g -75 k-secalin
Q9FR41
436
a
QQPQQPFP (32×)
38 22
6.1
1.6
4.8
5.3
g -hordein
P17990
286
m
QPQQPFP (15×)
28 17
7.7
3.1
7.0
7.3
B-hordein
P06470
274
a
QQPFPQ (13×)
30 19
7.3
2.9
8.0
6.2
avenin
Q09072
203
m
PFVQQQQ (3×)
33 11
8.4
2.0
8.9
8.3
a
a
aggregative,
m
monomeric
b
One-letter-code for amino acids
c
Basic unit frequently modified by substitution, insertion, and deletion of single amino acid
residues
d
Gellrich et al. [
65
]
The nomenclature of types is rather confusing and inconsequential. On the one
hand prolamins have been termed according to their electrophoretic mobility in acid
polyacrylamide gel electrophoresis (PAGE) with band regions designated as w
(lowest mobility), g (medium mobility), and a / b (highest mobility). On the other
hand, the nomenclature is based on their apparent sizes (after reduction of disulfide
bonds) as indicated by sodiumdodecyl sulfate (SDS-) PAGE; examples are HMW-
and LMW-glutenin subunits (GS), HMW-secalins, D-, C-, and B-hordeins. Because
of the different importance of HMW-GS for the bread-making quality of wheat,
single subunits have been numbered according to their mobility on SDS-gel
electrophoresis (original nos. 1-12), the genome (1A, 1B, or 1D), and the type (x or y);
examples of nomenclature are HMW-GS 1Ax1, 1Bx7, and 1Dy10 [
62
] .
The HMW group contains HMW-GS of wheat, HMW-secalins of rye, and
D-hordeins of barley (Table
2.4
); this type is missing in oats. HMW-GS and HMW-
secalins can be subdivided into the x-type and the y-type. The proteins comprise
around 600-800 amino acid residues corresponding to MW of 70,000-90,000.
