X ray generator

A 5 μL droplet of each peptide-analogue solution was placed between two aligned siliconized glass rods mounted on a glass slide, spaced approximately 2 mm apart and oriented horizontally, as collinearly as possible. Each sample was allowed to air-dry slowly at ambient temperature and humidity for approximately 30 min to form an oriented fiber suitable for X-ray diffraction. The X-ray diffraction patterns were collected using a SuperNova-Agilent Technologies X-ray generator equipped with a 135-mm ATLAS CCD detector and a 4-circle kappa goniometer (CuKα high-intensity X-ray micro-focus source, λ = 1.5418 Å), operated at 50 kV, 0.8 mA, installed at the Instruct-EL hub, Institute of Chemical Biology, National Hellenic Research Foundation, which is part of the national research infrastructure on structural biology Inspired. The oriented fiber sample was mounted onto the goniometer, and the specimen-to-film distance was set at 52 mm, with an exposure time of 400 s. Each X-ray diffraction pattern was initially viewed using the CrysAlisPro v. 171.40.67a software [24 ] and consequently displayed and measured with the aid of the iMosFLM v. 7.3.0 software [25 (link)].

A total 2.5 mol/L of AtPNP-A_36–69 aqueous solution was incubated for two weeks, to form viscous solutions, which facilitate the formation of oriented fibers. A droplet (5 μL) of the AtPNP-A_36–69 fibril-containing solution was placed between aligned glass capillaries with wax-covered ends, spaced 2 mm apart and mounted horizontally on a glass slide, as collinearly as possible. The sample was left to air dry at ambient temperature and humidity, for 30–60 min in order to form an oriented fiber, suitable for X-ray fiber diffraction [76 ]. The diffraction pattern was collected using a SuperNova-Agilent Technologies X-ray generator equipped with a 135 mm ATLAS CCD detector and a 4-circle kappa goniometer, at the Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation (CuKa high-intensity X-ray micro-focus source, k 51.5418 Å), operated at 50 kV, 0.8 mA. The oriented fiber sample was mounted onto the goniometer. The specimen-to-film distance was set at 52 mm, whereas exposure time was set to 400 s [77 (link)]. The X-ray patterns were initially viewed using the program CrysAlisPro [78 ] and subsequently displayed and measured with the aid of the program iMosFLM [79 (link)].

X-ray irradiation was performed using an X-ray generator (Varian, USA), emitting at a fixed dose rate of 4 Gy/min. The energy of the X-rays used to irradiate the cells was graded as 0, 2, 4, 6, and 8 Gy.