The enzymes used in this experiment are only a partially purified pyruvate kinase preparation. This is because complete purification would strip away co-factors and co-enzymes that are necessary for enzyme activities. However, all substrates used in the assay are pure.
i) Can you suggest any possible contaminating enzyme that might directly interfere with this assay? (Hint: Assume no membranes are present in the preparation.)
ii) Give a balanced equation for any reaction catalysed by a contaminating enzyme, including all cofactors and metal ion requirements.
iii) If present, how would this contaminating enzyme affect the assay?
iv) What assay would you carry out to determine the presence of such a contaminating enzyme this partially purified preparation?