Now I'm not quite sure how to help you (or if I can), I'll need a data description first.
How are your SNiP's quantified?
How are your protein levels quantified?
Categorical, ordinal, continuous ect ect
Secondly how is your response distributed then?
It of course depends on all of the above, but if you were thinking of running an regression or ANOVA type analysis remember that only your residuals must be normally distributed. The error around the model should be normal, the response itself not (necessarily).