Biomedical Engineering Reference
In-Depth Information
TABLE 14.1
Physicochemical Properties of Some Enzymes
Molecular
Weight (kDa)
Isoelectric Point
(IEP) (p
I
)
Stable pH
Range
Optimal pH
Optimal
Temperature (
ºC
)
Enzymes
Glucose oxidase (GOD)
(
Aspergillus niger
)
150-186
∼
4.9
3.5-6.5
5.6
30-50
Cholesterol oxidase (COD)
(
Pseudomonas
)
60
5.1-5.4
4.0-11.0
7.0
4-60
Acetylcholinesterase (AChE)
260
—
7.5-8.5
8.0
∼
30
Horseradish peroxidase (HRP)
∼
42
7.2
4-10
6.5
∼
40
Lactate dehydrogenase (LDH)
(heart muscle)
135
4.5-4.8
—
8.75-9.0
∼
32
Pyruvate oxidase (PyOD)
(
Lactobacillus plantarum
)
260
—
—
5.7
30
TABLE 14.2
Special Catalytic Property of GOD to the Oxidation of
β
-
D
-Glucose
Substrates
Relative to Glucose
a
(%)
β-d-Glucose
100
2-Deoxy-d-glucose
25-30
4-
O
-methyl-d-glucose
15
6-Deoxy-d-glucose
10
4-Deoxy-d-glucose
2
2-Deoxy-6-fl uoro-d-glucose
1.85
3,6-Methyl-d-glucose
1.85
4,6-Dimethyl-d-glucose
1.22
3-Deoxy-d-glucose
1
6-
O
-methyl-d-glucose
1
α-d-Glucose
0.64
Mannose
0.2, 1
Altrose
0.16
Galactose
0.08
Xylose
0.03
Idose
0.02
a
Activity relative to β-d-glucose in percentage.
Source
: Leskovac, V., Trivić, S., Wohlfahrt, G., Kandrač, J., and Peričin, D.,
Int. J. Biochem.
Cell. B.
, 37, 731, 2005. With permission.
GOD is a fl avin-containing glycoprotein. The fungal enzyme is a homodimer made up of two
identical subunits of molecular weight (kDa) approximately 80,000 Da each [4]. Dissociation of
subunits is possible only under denaturing conditions accompanied by the loss of the coenzyme
fl avin adenine dinucleotide (FAD) [5].
GOD has a special property to catalyze the oxidation of β-d-glucose [6] (detailed in Table 14.2).
This oxidation is a representative two-step process of enzyme reaction [7] including oxidation of
