Fig. 5: NicA2 v321 degrades plasma nicotine in rats.
From: Directed evolution unlocks oxygen reactivity for a nicotine-degrading flavoenzyme
Adult Wistar rats (N = 48, equal numbers of males and females) were exposed to nicotine (free base) at a concentration of 3.15 mg per kg (body weight) per d to achieve a chronic blood nicotine level of 50 ng ml−1 or were administered 0.9% saline for 7 d via osmotic minipump. Rats were injected with 0.1 mg per kg (body weight) wild-type NicA2, 1 mg per kg (body weight) wild-type NicA2, 0.1 mg per kg (body weight) NicA2 v321 or 1 mg per kg (body weight) NicA2 v321 at the time of minipump implantation and again every 48 h. Blood was collected from animals at 1 and 5 d after minipump implantation, and plasma nicotine levels were analyzed by liquid chromatography–MS (LC–MS). Because we did not observe differences between sexes, the data reflect both sexes combined. a, Plasma nicotine levels after 1 d of nicotine exposure (24 h after injection of either vehicle or NicA2 treatments); additional statistical significance values not shown on the figure: for naive versus vehicle, 0.1 mg per kg (body weight) wild type, 1 mg per kg (body weight) wild type and 0.1 mg per kg (body weight) NicA2 v321, all P < 0.0001; for 1 mg per kg (body weight) NicA2 v321 versus vehicle, 0.1 mg per kg (body weight) wild type, 1 mg per kg (body weight) wild type and 0.1 mg per kg (body weight) NicA2 v321, P < 0.0001; n = 8 per treatment group and n = 7 for the 1 mg per kg (body weight) NicA2 v321 group; ND, s.e. not determined. b, Plasma nicotine levels after 5 d of nicotine exposure (24 h after injection of either vehicle or NicA2 treatments); additional statistical significance not shown on the figure: naive versus vehicle, 0.1 mg per kg (body weight) wild type, P < 0.0001; naive versus 1 mg per kg (body weight) wild type, P = 0.03; naive versus 0.1 mg per kg (body weight) NicA2 v321, P = 0.004; 1 mg per kg (body weight) NicA2 v321 versus 0.1 mg per kg (body weight) wild type, P < 0.0001; n = 8 per treatment group and n = 7 for the 1 mg per kg (body weight) NicA2 v321 and 1 mg per kg (body weight) wild type groups. Data were analyzed by one-way analysis of variance with Tukey’s multiple comparisons post hoc tests. The mean is plotted with error bars that represent the s.e.
