9.0) optimal pH, more than two pH units higher than that of vertebrate AANATs. Conclusions The substrate selectivity profiles of bfAANATα and δ' are relatively broad, including alkylamines, arylalkylamines and diamines, in contrast to vertebrate forms, which selectively acetylate serotonin and other arylalkylamines. Based on these features, it appears that amphioxus AANATs could play several roles, including detoxification and biogenic amine inactivation. The presence of seven AANATs in amphioxus genome supports the view that arylalkylamine and polyamine acetylation is important to the biology of this organism and that these genes evolved in response to specific pressures related to requirements for amine acetylation."/>
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Figure 4 | BMC Evolutionary Biology

Figure 4

From: Evolution of AANAT: expansion of the gene family in the cephalochordate amphioxus

Figure 4

Determination of CoA-HNE binding and off-rate. A. Quenching of tryptophan fluorescence as a function of the binding of inhibitor CoA-HNE by recombinant GST-bfAANATα. Binding was not observed in the presence of 4 M guanidine, which denatures the protein. B. Off-rate of CoA-HNE from the active site of the enzyme was measured by displacement with another inhibitor. Fluorescence anisotropy is shown as a function of time. Samples of proteins (2 μM) were 90% saturated with CoA-HNE. After 5 min the fluorescence anisotropy was measured. At t = 200 s, CoA-T was added to a final concentration of 170 μM and fluorescence anisotropy measurement was resumed. oAANAT data from a previous study are included for comparison [15]. Data are presented as the mean ± S.E.M (N = 3). For further details see Methods.

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