%yield of enzyme in protein purification greater than 100% ?

[Phan Na Yên]

Hi all,

 

I got stucked in my report of protein purification. My sample protein mixture (catalase + lysozyme in 5mM phosphate buffer, pH 7.5) is separated by DEAE-Sepharose chromatography. after separation, my fraction has enzyme activity was 217iu whereas crude sample is 135iu.That means %yield of enzyme > 100%.

It doesn't make any sense 'cause %yield is supposed to be less than or equal to 100%, right?

 

I'm quite sure that the whole experimental process there is no error or mistake at all. Does any one can suggest any solution for me in this case?

 

Thank you so much!

[Elite Engineer]

When you purified your protein, you removed a sizable amount of other unwanted proteins and lipids etc. The decrease in these other components allowed your enzyme to have increased interactionswith its substrate, therefore increasing it's acivity. However a 60% increase is very high..unless your sample was HEAVILY contaminanted and you removed ALOT of garbage...or you may have measured or calculated the enzyme's activity incorrectly. What was the specific activity of your enzyme?

 

(the same thing happened to me when I purified PON1 enzyme..but my increase in activity was a modest 2-4% increase)

 

~EE

Edited April 4, 2015 by Elite Engineer

[BabcockHall]

Experimental error should not be categorically ruled out. Enzyme assays may be run outside the limits of where they respond linearly to the concentration of enzyme, for instance. If you calculated the total number of units by finding the specific activity and multiplying by the number of milligrams of protein, then the protein assays are another potential source of error.