isolation of enzymes?

Answer 1

Design an antibody that targets specifically your intended enzyme. Then, do a "pull-down".

The question is about Isolating the enzymes, not producing the enzymes, so I don't think over-expression systems is what they are looking for here. Moreover, over-expression of the enzyme in say bacteria may or may-not give rise to the same enzyme that you want to isolate. Anyway, to isolate something, one needs to specifically target the protein and antibodies are the best in doing so. You need not raise the antibodies yourself, you can buy them commercially.

Answer 2

BambooBoy that's true only if you already know the enzyme and you have enough purified at a high degree of purity in order to raise antibodies against it.
However, if you know the sequence you can actually clone it, over-express it fused with a tag and purify it by affinity chromatography. No need for antibodies.

If you don't know anything about the enzyme you just follow its enzymatic activity with a proper assay and try to purify it with various methods like precipitation with pH or ammonium sulphate, different types of chromatography etc. Also depends on the organism and localization of the enzyme (is it in an organelle, cytoplasm, membrane?) and its post-translational moification, if any. E.g. if you want a mammalian heavily glycosylated enzyme you can't really use E.coli as an expression system.

The question is too vague too provide a more suitable answer.

Answer 3

I once had to do something like this. From memory we used small cylinders (called (elution?) columns).

These columns contained beads that have Anti-enzyme-Abs on the them. You put a solution containing the target enzmye through it and the enzmye sticks to the antibody. You put through a second solution that causes the enzymes to detach from the antibodies (this process is called elution I believe).

This is just one method. You can also you some sort of eletrophoresis.