Question

Which of the following is not correct about the X-ray Crystallography?

(a) In x-ray protein crystallography, proteins need to be grown into large crystals in which their positions are fixed in a repeated, ordered fashion

(b) The protein crystals are illuminated with an intense x-ray beam

(c) The x-rays are deflected by the electron clouds surrounding the atoms in the crystal producing a regular pattern of diffraction

(d) The protein crystals are illuminated with an intense infrared beam

I have been asked this question during an interview.

The origin of the question is Protein Structure Basics topic in portion Structural Bioinformatics of Bioinformatics

Answer 1

The correct option is (d) The protein crystals are illuminated with an intense infrared beam

The explanation: The diffraction pattern is composed of thousands of tiny spots recorded on a x-ray film.

The diffraction pattern can be converted into an electron density map using a mathematical procedure known as Fourier transform. To interpret a three-dimensional structure from two-dimensional electron density maps requires solving the phases in the diffraction data.