MadSci Network: Biochemistry |

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Dear Nerys,

On the assumption that you are a sixth-form student doing an A-level investigation, then the level of work you are proposing is well above A- level standard and the Michaelis-Menten equation would not be required.... However, when you do the practical, you will get a RATE as your results - so many bubbles of oxygen per minute.

(Bubbles are better than cm^{3}, as with very small volumes, the inaccuracy
of measurement with a gas syringe is greater than with bubbles. Each
bubble has a constant volume, assuming the same pressure of water and the
same diameter delivery tube. At VERY high rates, this may not apply since
the next bubble 'stretches' the diameter of the tube from which the bubble
comes...but that is by-the-by)

Once you have a rate, re-arranging the equation will give you the constant (rate over conc H202 x conc catalse). This will vary with temperature - in practice, just read off the slope of the graph (peak rate against H2O2 conc) and this will give you the number you need......

Hope this helps - I am 'only' an A-level teacher, so if you are a uni student, you may need more... Try http://www.catalase.com/catali nks.htm for a really detailed look at the enzyme (yes, this enzyme really does have a 'dot com'!!

This web-site has the exact answer you are looking for (I think..) http:// www.courseworkbank.co.uk/coursework/hydrogen_peroxide_catalase_2291/.

Hope all's well in Wales (shame about the rugby....!)

Ian

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