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Immobilising enzymes
- Adsorption
- Enzyme molecules are mixed
with the immobilising support
and bind to it due to a
combination of hydrophobic
interactions and ionic links
- Adsorbing gents used include porous carbon, glass beads, clays and resins
- Because the bonding forces are not particularly strong, some
enzymes can become detached.
- However, provided the enzyme molecules are held so that their active site is not
changed and displayed, adsorption can give very high reaction rates.
- However, provided the enzyme molecules are held so that their active site is not
changed and displayed, adsorption can give very high reaction rates.
- Because the bonding forces are not particularly strong, some
enzymes can become detached.
- Adsorbing gents used include porous carbon, glass beads, clays and resins
- Enzyme molecules are mixed
with the immobilising support
and bind to it due to a
combination of hydrophobic
interactions and ionic links
- Covalent bonding
- Enzyme molecules are covalently bonded to a support, often by covalently
linking enzymes together to an absolute material (clay) using a cross-linking
agent like gluteraldehyde or sepharose.
- This method does not immobilise a large
quantity of enzyme but binding is very strong
so there is very little leakage of enzyme from
the support.
- Enzyme molecules are covalently bonded to a support, often by covalently
linking enzymes together to an absolute material (clay) using a cross-linking
agent like gluteraldehyde or sepharose.
- Entrapment
- Enzymes may be trapped in a bead network or in a cellulose fibre network.
- However reaction rates can be reduced because substrate molecules need to get through the trapping barrier.
- This means the active site is less easily available than with adsorbed or covalently bonded enzymes
- This means the active site is less easily available than with adsorbed or covalently bonded enzymes
- However reaction rates can be reduced because substrate molecules need to get through the trapping barrier.
- The enzymes are trapped in their natural state.
- Enzymes may be trapped in a bead network or in a cellulose fibre network.
- Membrane separation
- Enzymes may be physically
separated by a partially permeable
membrane.
- Most simply, the enzyme solution is held at one
side of the membrane whilst substrate solution is
passed slong the other side.
- Product molecules are small enough
to pass back through the membrane.
- Product molecules are small enough
to pass back through the membrane.
- Substrate molecules are small enough to pass through the membrane so
that the reaction can take place.
- Most simply, the enzyme solution is held at one
side of the membrane whilst substrate solution is
passed slong the other side.
- Enzymes may be physically
separated by a partially permeable
membrane.
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