PMC

a Dimensions of the trap, inserts front view. 16 cm wide × 80 cm high; 16.5 cm diameter (circular opening of the funnel), 56 cm depth of the trap, 81 cm long × 40 cm diagonal (large opening of the funnel); 10 cm distance of the small opening of the funnel from the backside of the trap. b Prototype 3 outside view inside a house, with circular funnel as entrance

a Dimensions of the trap, inserts front view. 16 cm wide × 80 cm high; 16.5 cm diameter (circular opening of the funnel), 56 cm depth of the trap, 81 cm long × 40 cm diagonal (large opening of the funnel); small circular funnel diameter 10.5 cm, distance from the beginning of the large circular to the end of small circular 9 cm and 10 cm distance of the small opening of the funnel from the backside of the trap. b Prototype 4 outside view inside a house, with small circular funnel entrance

Cross-sectional view of the TIMS entrance funnel, analyser section and exit funnel.

(a) Cross section through the active site of FALDH. The NAD-binding pocket and the substrate funnel positioned on opposite sides of the enzyme and merge in its central active site. Active site residues are indicated in red (Asn-112, Glu-207, Cys-241 and Glu-331). The electron density found in the substrate funnel is indicated in yellow. The electron density mesh was generated at 1.2 sigma within 1.6 Å around a hexadecanoic acid molecule, which was previously modelled into the electron density. The gatekeeper helix, covering the substrate funnel entrance is shown in green. The substrate funnels of (b) FALDH and (c) ALDH3A1 (3sza) were characterized using the MOLE toolkit for PyMOL. While in FALDH, the additional gatekeeper helix (shown in green) creates a kink in the channel (shown in yellow), the wide, linear arrangement of the substrate funnel entrance of ALDH3A1 is not restricted.