Figure 2.

Time course of luminescence produced by plasma membrane (3.3 μg of protein), supernatant II (0.12 μg of protein), and S100 (6.0 μg of protein). Reaction components (protein, 100 μm NADH, 0.02% Triton X-100, 0.4 mm lucigenin, plus buffer to make 1.0 mL) were combined at time 0 and placed in a scintillation counter, and the luminescence, integrated over 1 min, was measured every 15 min. Background values were from mixtures of all reaction components except protein. Also shown is the luminescence produced by NADH, Triton X-100, and lucigenin in the presence of 50 μm DTT (the concentration in reactions receiving S100).