Chemistry Reference
In-Depth Information
Table 4.1
Criteria for robust immobilised enzymes, adapted from ref. [
9
] with permission from
Elsevier
Parameter
Requirement
Benefits
Non-catalytic
Suitable particle size
Ease of separation
Easy fabrication
Flexibility in reactor design
High mechanical and chemical
stability
No decomposition, loss of support
Catalytic
High specific activity (U/g)
High productivity and space-time yield
High selectivity
Less by-products, easy downstream
processing
Substrate specificity (broad)
Applicable to a wide substrate chemistry
Thermal, chemical, conforma-
tional and operation stability
Low cost operation
Immobilised
enzyme
Recyclability
Economical processing
Reproducibility
Quality assurance
Facile design
Short times for process development
Other
Low volume
Low handling and capital costs
Easy disposal
Less pollution
Safe for use
Safe
usually be utilised in fixed-bed type reactors or easily removed by simple filtration
protocols [
7
].
In order to design and develop immobilised biocatalysts, the biocatalyst needs
to perform “non-catalytic” and “catalytic” functions effectively and several criteria
have been suggested for robust immobilised enzymes (Table
4.1
) [
9
]. The cata-
lytic functions include efficient catalysis, productivity, substrate/product selectivity
and yield, while non-catalytic functions comprise of support's stability (mechani-
cal, chemical and thermal), porosity and reusability. A range of methods have been
outlined in the literature for improving the catalytic and non-catalytic functions of
immobilised enzymes such as specific activity, stability and selectivity [
3
,
4
,
9
,
10
]
and are not detailed herein.
As knowledge about immobilised systems increases, so too do the applications.
Current applications include the production of useful substances (particularly in
the pharmaceuticals and food and drinks industries) and waste treatment (water in
particular). In these areas, product purity is important, hence using immobilised
enzymes can result in purer products since the product will be effectively enzyme
free [
8
]. Furthermore, immobilisation of enzymes offers their use in the fabrication
of analytical devices, as adsorbents in purifying proteins and enzymes, as a platform
for performing solid phase protein chemistry and for controlled release of protein
drugs [
10
].
