Enzymes- Michaelis Constant

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Nicolodn
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Enzymes- Michaelis Constant

Post by Nicolodn » Sun Sep 12, 2010 10:13 am

Would Enzyme in a dog and the same enzyme in a giraffe have the same Michaelis constant? WHY?
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JackBean
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Post by JackBean » Sun Sep 12, 2010 10:17 am

Probably not THE SAME, but it might be pretty similar
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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Post by JackBean » Sun Sep 12, 2010 10:19 am

Oh yeah and why... well, because they (the enzymes), probably come from the same ancestor, but have diversified a while ago, so they won't have identical primary structure, but still it will be pretty similar (but depends on each case)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

Nicolodn
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Post by Nicolodn » Sun Sep 12, 2010 10:20 am

Okay, thanks. So, they will be slightly different because of differing structure?
I thought that to, but, if they have a different structure, doesn't that make it a different enzyme? That was what I have been confused about. Also, because the same enzyme from a different source has different optimum pH, temp,etc right?

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Post by JackBean » Sun Sep 12, 2010 10:32 am

I'm talking about primary structure i.e. the AAs sequence, but the 3D fold will be highly similar (maybe some loops will be missing etc.)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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Post by Nicolodn » Sun Sep 12, 2010 10:37 am

So, because the charges of the aa are different, then the amount of substrate able to bind to the active site will be less?

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Post by JackBean » Sun Sep 12, 2010 11:31 am

Well, you cannot say less, as you're not refering to any particular enzyme ;) But yes, it will be PROBABLY sligthly different
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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Re: Enzymes- Michaelis Constant

Post by Nicolodn » Sun Sep 12, 2010 1:05 pm

Sorry, could you tell me why the change in primary structure can change Km? :?

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Post by JackBean » Sat Sep 18, 2010 8:48 pm

Primary structure = sequence of amino acids => by changes of amino acids in the binding side you will influence the affinity and thus K_M
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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