Enzymatic activity assay.

A. Native and recombinant proteins were analyzed for LKR and SDH activities under conditions of excess concentrations of all LKR substrates or all SDH substrates, respectively. Data are presented as units/mg protein. Mean±S.D (n = 3). B. Separation of LKR and SDH activities by native-PAGE gel electrophoresis. Samples of partially purified midgut and ovaries, and recombinant His-LKR/SDH were separated by native PAGE and subsequently stained for SDH and LKR activity. In the control gel, samples incubated without L-lysine and saccharopine are labeled “Lys-” and “Sacch-”. In the LKR and SDH activity staining gel, the samples are labeled “Lys+” and “Sacch+”. Lane 1, midgut; lane 2, ovary; lane 3, His-LKR/SDH. C. Optimum pH of LKR/SDH native protein.