2
$\begingroup$

I am working with the enzyme Cu/Zn Superoxide (SOD1) and i am quantifying them in ng/ml. However, most past studies has SOD1 quantified in unit/mg or unit/ml, and i need to compare the SOD1 level of my study with those past studies. Is there a way to standardize these units?

Thank you!

Improve this question
$\endgroup$
1
  • 1
    $\begingroup$ You need a value for the specific activity of the purified enzyme, in units/ mg (or similar). Also you need to check on the definition of a unit of activity for your enzyme since this is empirically defined. $\endgroup$
    – Alan Boyd
    Commented Feb 16, 2014 at 16:17

2 Answers 2

Reset to default
1
$\begingroup$

There is no archaism in measuring enzyme amounts in units. Unit definition for SOD and a protocol can be found here (from Sigma): https://www.safcglobal.com/technical-documents/protocols/biology/enzymatic-assay-of-superoxide-dismutase.html :

"One unit will inhibit the rate of reduction of cytochrome c by 50% in a coupled system, using xanthine and xanthine oxidase ..."

I don't think, there is a good way to convert ng's to units, since one measures either mass or enzymatic activity, and the correlation between them is not always consistent. Units should be much more reliable in terms of comparisons with other studies, if you are not considering your enzyme as, e.g., a nutritious substance.

Improve this answer
$\endgroup$
0
$\begingroup$

Quantification is a measure of your protein quantity and units/ml or mg is a unit of protein quantity. These are two different things. You need to set a rxn of SOD with its substrate and get activity which is proportional to your consumption of substrate. Then u will get the activity of your protein which will be in units/mg or ml

Improve this answer
$\endgroup$
2
  • $\begingroup$ But: This is only valid for a certain batch, since the activity of protein preparations varies between batches. Thats why we have this units, which is not a very good thing. But better than nothing. $\endgroup$
    – Chris ♦
    Commented Feb 17, 2014 at 13:42
  • 1
    $\begingroup$ Right sir....:) $\endgroup$
    – user5741
    Commented Feb 17, 2014 at 20:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .