Table 2.

Effect of 0.5 mM riboflavin and/or light on the XET reaction in solution.

Reaction mixture	[3H]Xyloglucan formed (cpm)
	Low light	High light
Enzyme + substrates	8861 ± 105	8942 ± 349
Enzyme + substrates + riboflavin	5390 ± 130	807 ± 63

Parsley enzyme extract was incubated with substrates (xyloglucan and [³H]XXXGol) in extremely low or ‘bright indoor’ light intensity (0.2 or 1100 lux, respectively), in the presence or absence of 0.5 mM riboflavin as a singlet oxygen generator. The yield of product ([³H]xyloglucan) was assayed after 2 h. Data are mean ± SE of 4 independent assays.