Dominant negative mutation: Tyr is usually mutate to ? - Site directed mutation (Apr/04/2006 )

Hi, everyone:

I am designing some dominant-negative mutations.
I want to inactive an enzyme by replace its active site Tyr to another Amino acid, but I don't know which one to choose. I found in papers, Tyr was usually changed to Phe, while sometimes it was changed to Ala. I wonder whether both of them are ok?
I also want to mutate Ser site, I got puzzled again.
Is there any rule to make such decision? Thank you!

Annabel

You have to think that you might change a lot of things by doing a mutation, not only you avoid the phosphorylation, but you may also change the structure of the protein.
Usually, you change tyrosine into Phe, because it's the same amino acid but without the hydroxyl group. Then you expect not to damage too much the structure of the protein (because there is still the aromatic group). I would say it's better than alanine.

on the other hand, it happens that even if you think you do it at best , like replacing cysteine by serine, the protein becomes toxic for the bacteria, and alanine is better . Sometime you have to try.

I would replace ser by ala.

here you can have a look on the structure of the amino acids