Point mutation causes increase in catalytic activity

Artem Evdokimov AEVDOKIMOZ at cinci.rr.com
Sat Feb 2 19:50:03 EST 2002


I know of quite a few cases of proprietary enzymes enhanced by point
mutations. Activity can be improved via several routes, not all of which
would change the active site. For example, if your enzyme is unstable then
your apparent 'specific actvity' can be improved by making it more stable,
In general, I think that evolution does not always optimize for MAXIMUM - it
prefers to drive things towards OPTIMUM. For example - consider proteolytic
enzymes - if they were all maximally active, who knows what havoc would this
cause in the living cell?

If you can tell us what enzyme you deal with, specifically, we might be able
to help you better.


""Tony Johnson"" <wissen0117 at hotmail.com> wrote in message
news:F158czzjk7YnLnxqDGr00015c87 at hotmail.com...
> Hi all,
> I have an interesting mutant in an enzyme from E. coli that causes an
> _increase_ in the catalytic rate.  The point mutation isn't in an area of
> the protein that, in my opinion, functions as a negative regulator of the
> catalytic activity.  Nor is it very close to the active site.  My question
> is: Can anyone think of another example where a single point mutation
> an increase in the catalytic rate?
> Of a more philosophical nature, in evolution, why wouldn't an enzyme
> to maximize its catalytic rate?  Especially from an organism that seems to
> be streamlined for efficiency (E. coli), doesn't an increase in catalytic
> activity of an essential enzyme translate into increased efficiency and
> survivability and, thus, fitness?  Or is my understanding of evolution a
> too simplistic?
> Thanks in advance,
> Tom
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