Biomedical Engineering Reference
In-Depth Information
Table 2.
Intrinsic rate constant and effectiveness factor values of
D
-amino acid oxidase immo-
bilized in calcium pectate gel studied by flow microcalorimetry [28]
Parameters
Cell loading concentration
(mg dry mass mL
-1
gelling suspension)
24.0
34.2
48.0
60.0
79.9
k
1
(min
-1
)
0.45
0.60
1.45
1.18
4.50
Thiele modulus,
F
(-)
3.08
3.55
5.52
4.98
9.73
Effectiveness factor,
h
(-)
0.66
0.60
0.44
0.47
0.27
loading on the activity and effectiveness of the biocatalyst.The advantage of this
approach is the ease and rapidity with which the experimental data are treated.
This is very useful for a simple comparison of the intrinsic activity of different
biocatalysts.
In spite of usefulness of the simplification obtained by decreasing the experi-
mental substrate concentration, many studies are aimed at the investigation of
kinetic properties of immobilized biocatalysts within broader concentration
ranges. In a previous paper [29], cells of
Escherichia coli
with penicillin acylase
activity were immobilized by entrapment in calcium pectate gel and tested on
the transformation of penicillin G to 6-amino penicillanic acid. Figure 9 shows
experimental data from a microcalorimetric investigation of the penicillin G
transformation in steady state.As appreciable particle-mass transfer was expect-
ed,the mathematical model that includes particle-mass balance was used.
Fig. 9.
Kinetic measurement of the calcium pectate gel immobilized penicillin acylase in the
flow microcalorimeter. Cell loading concentrations (mg of dry weight per mL of gelling
suspension): (
) 11.9; (
) 23.7; (
) 29.6 [29]
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