| Feature |
Immobillization System |
| |
Adsorption |
Covealent binding |
Entrapment |
Membrane confinement |
Matrices (examples) |
Ion-exchange
matrices, clays,
glasses, etc. |
Sepharose,
cellulose,
acrylamide, etc. |
Acrylamide,
cellulose
acetate, etc. |
Semipermeable
membranes, e.g.
hollow-fibers,
lipsomes, etc. |
| Preparation |
Simple |
Difficult |
Difficult |
Simple |
| Immobilization
mechanism |
Hydrophobic
effects, salt links |
Covalent bonds |
Trapping in
Gel/fibre;
even covalent
bonds |
Confinement in
a semipermeable
membrane |
| Binding force |
Variable |
Strong |
Weak |
Strong |
| Enzyme loading |
High (Ca. 19/9
matrix) |
Small (Ca. 0.02
gig matrix) |
- |
- |
Enzyme leakage
during use |
Yes |
No |
Yes |
No |
| Applicability |
Wide |
Selective |
Wide |
Very wide |
| Problems during
operation |
High |
Low |
High |
High |
| Matrix effects on
enzyme |
Yes |
Yes |
Yes |
No |
| Diffusional
barriers * |
Absent |
Absent |
Large |
Large |
| Protection from
microbial attack |
No |
No |
Yes |
Yes |
| Cost |
Low |
High |
Moderate |
High |
