Chemistry Reference
In-Depth Information
Table 2 The molecular weight (MW) and isoelectric point pI of the five
dominant protein species in the egg yolk livetin fraction as determined
by two-dimensional SDS
PAGE and subsequent mass spectrometry
Observed MW
(kDa)
Observed
pI
Theoretical MW
(kDa)
a
Theoretical
pI
a
Spot
Protein
1 Ovotransferrin
(conalbumin)
80
6.5
7
75.8
6.69
2
Immunoglobulin G, heavy
chain
b
65
70
6.5
8
60
70
6
7
3
Serum albumin (a-livetin)
65
5
5.7
67.2
5.35
4 Yolk plasma glycoprotein
YGP42
40
5.3
5.8
31.4
5.88
5 Yolk plasma glycoprotein
YGP40
35
5.5
6.3
31.0
6.16
Source: Modified from ref. 12.
a
Not taking into account any post-translational modifications, e.g., glycosylation or phosphor-
ylation.
b
Theoretical values for IgG are only approximate due to the inherent immunoglobulin heteroge-
neity.
rate of Q
c
(0)
ΒΌ
1.0 mL min
1
and then the flow rate was reduced exponentially
with a set time constant, e.g., a half-life of 4 min. After 24 min of elution the
cross flow rate was set to zero and the channel flushed without any cross flow
for 5 min before the next analysis. The carrier liquid for the separation was
10 mM NaNO
3
with 0.002 wt.% NaN
3
. The molar mass and the rms radius
were obtained by Berry's method
17
by fitting a straight line to the data obtained
at scattering angles of 43
901. (The lowest scattering angles of 14-351 were
not included as these gave data that were too imprecise.) A dn/dc value of
0.146 mL g
1
was used,
18
and the value of the second virial coefficient was
taken as negligible.
30.3 Results
30.3.1 Total Adsorption of OSA-Starch
The emulsification performance is shown in Figure 2 as emulsion surface area
created (A) versus the initial OSA-starch concentration (C
0
). These results show
that it is possible to create an emulsion with the OSA-starch as the sole
emulsifier. If we assume that the amount of available emulsifier limits the
effectiveness of the emulsification, then the surface area should increase (i.e.,
droplet diameter should decrease) linearly with the initial emulsifier concen-
tration. For samples B86-10 and B27-21 the amount of surface area created
during emulsification was found to increase strongly with increasing initial
OSA-starch concentration, but for sample B39-22 the surface area increase is
less pronounced up to a concentration of
1.25 mg mL
1
. Replicates of
sample B39-22 also exhibited a rather large variation in the surface area
B
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