Fig 4.

(A to D) pH dependency of CDH IIA and CDH IIB activities for the artificial electron acceptors ferrocenium hexafluorophosphate (A), cytochrome c (B), 1,4-benzoquinone (C), and DCIP (D), using lactose as the electron donor. Circles, CDH IIA; triangles, CDH IIB. Activities from pH 2.5 to 9 were measured with McIlvaine buffer. (E and F) pH-dependent interaction of CDH IIA (E) and CDH IIB (F) with the competitive substrates cyt c and GH61-3. Diamonds, turnover rates of cyt c in the absence of GH61-3; squares, turnover rates of cyt c in the presence of GH61-3; filled circles, ratio of the turnover numbers, which is used as a measure of the inhibition of cyt c reduction by GH61-3.