Figure 3.

Kinetics of the electron transfer from pc or cyt c₆ to P700⁺. Absorbance transients monitored as ΔA₈₁₇ induced by a laser flash in PSI particles isolated from the four mutants, K12P, K16Q, K23Q, and K30Q (from top to bottom) in the presence of 300 μM cyt c₆ (Left) or 300 μM pc (Right). The cuvette contained PSI particles at a concentration of 90 μg Chl per ml, 0.05% (wt/vol) β-dodecyl maltoside, 10 mM MgCl₂, 30 mM 3-(N-morpholino)propanesulfonic acid (pH 7.0), 1 mM sodium ascorbate, 0.1 mM methylviologen, and 0.2 mM diaminodurene. The absorbance transients measured in the absence of donor proteins are shown as control by dotted traces. Vertical broken lines separate regions recorded with a different time base. The half-lives of the kinetic components attributed to the donor proteins are as follows: in the presence of 300 μM cyt: c₆ K12P, 4 μs and 95 μs; K16Q, 4 μs and 178 μs; K23Q, 4 μs and 393 μs; K30Q, 4 μs and 169 μs, and in the presence of 300 μM pc: K12P, 4 μs and 45 μs; K16Q, 4 μs and 128 μs; K23Q, 4 μs and 239 μs; K30Q, 4 μs and 86 μs.