Protein Purififcation - (May/02/2008 )

Why is it necessary to use 90% pure protein for sequencing and only 20% for enzyme activity?

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q1: to get no impurities by other polypeptides which may disturb sequencing signals
q2: depends on specificity of enzyme reaction which discriminates other non-relevant enzyme reactions

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Thanx Bearer but could you explain more please about the second point (20 % for enzyme activity) because i don't understand it much.

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the purer the better to test an enzyme if you know its condition of activation and substrates; however, 20% purity or less may be sufficient if no similar enzyme reactions are abundant, and do not interfer; some impurity may be helpful if you do not know the activating co-factors which may be part of the impurity...

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