- Enzyme molecules mixed with immobilising support.
- They bind to it due to a combination of hydrophobic interactions and ionic links.
- Adsorbing agents include: porous carbon, glass beads, clays and resins.
- Weak bonding forces can lead to leakage (detachment of enzyme molecules.)
- Attaching enzymes without denaturing and displaying the active site leads to high reaction rates.
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- Enzyme molecules covalently bonded to support.
- Covalently linked enzymes are linked to an insoluble material using a crosslinking agent (gluteraldehyde or sepharose.)
- Does not immobilise large quantities of enzyme.
- Strong binding so leakage is small.
- Covalent bonding can denature actibe site.
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- Enzymes may be trapped in gel bead or cellulose fibre network.
- Trapped in natural state so active site will not be affected.
- Reduced reaction rates as substrate must pass through barrier to reach active site and form enzyme-substrate complex.
- Active site less easily available than adsorption or covalent bonding.
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- Enzymes and substrates may be separated by a partially permeable membrane.
- Enzymes are held on one side of membrane, substrate passed along opposite side.
- Enzyme molecules are too large to pass through membrane.
- Substrate molecules are small enough to pass through membrane.
- Product molecules are small enough to pass back through the membrane.
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