The effects of cysteine levels and reaction periods on the product profile. Linoleic acid (600 μM) was incubated with yeast extract expressing Nb-9-LOX and different concentrations of cysteine at 35°C for 1 hour. The product was detected by LC-MS. (A) Ultraviolet detection at 234 nm. Peak 1, 9-HPOD; peak 2, 9-HOD. The concentrations of cysteine are given. (B) Relative amounts of 9-HPOD and 9-HOD calculated from LC-MS analysis of peak 1 (9-HPOD) and peak 2 (9-HOD) from (A). (C) Relative amounts of 9-HPOD and 9-HOD calculated from LC-MS analysis of products formed from the reaction containing 600 μM of linoleic acid, yeast extract expressing Nb-9-LOX, and 2.4 mM of cysteine at 35°C after different reaction periods. The production of 9-HPOD was monitored at m/z 335 [M+Na]+, and of 9-HOD at m/z 319 [M+Na]+. The highest amount was defined as 1. Each bar represents the mean and standard error of three replicates.