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enzyme activity, please help

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enzyme activity, please help

Postby Fa23 » Tue Nov 16, 2010 8:51 pm

can an enzyme have a negative activity? i had to do this lab and the values i got produce a negative value for activity. so i will just list here a few values that give a negative activity

Optical Density at 0 time, OD after 60s
0.91, 0.92
0.91, 0.93

to find activity you do the following:

(OD at 0 time - OD after 60s)/0.001

but doing this yields a negative value for the enzyme activity, is that okay?

thanks
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Re: enzyme activity, please help

Postby canalon » Tue Nov 16, 2010 8:57 pm

Fa23 wrote:(OD at 0 time - OD after 60s)/0.001

Here is your mistake.
I assume that your enzyme activity cause an increase of OD so if you want to measure how much the OD has increased you sure got it the wrong way...
Patrick

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any proof. (Ashley Montague)
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Re: enzyme activity, please help

Postby Fa23 » Wed Nov 17, 2010 12:06 pm

got it the wrong way...


so just flip it around...thats fine and all for this set but the rest of the values are not increasing, either they are steady or they are actually lower than O.D at time 0
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Postby Deat » Wed Nov 17, 2010 12:10 pm

Maybe there was human error when collecting the results, in any case, completley restart your equations and keep a log of your equations so that you can quickly identify the error. This would be the best way as it would help prevent future errors.
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Postby JackBean » Thu Nov 18, 2010 6:50 am

actually, the absorbance could decrease as well, if the color substance was consumed ;) For example the cytkinin oxidase/dehydrogenase may be measured by decoloration of electron acceptor DCPIP ;)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Re: enzyme activity, please help

Postby Trevorwin » Fri Sep 16, 2011 7:28 am

Hello!! and how can enzyme inhibitors irreversibly inactivate enzymes??
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Postby JackBean » Fri Sep 16, 2011 10:12 am

by denaturation, binding to crucial residues etc.
http://www.biolib.cz/en/main/

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