Radial distribution functions. (A) The pair radial distribution function g(r) between backbone amide hydrogen HB and water oxygen OW (solid), as well as urea oxygen OU (dash). (B) The pair radial distribution function g(r) between backbone carbonyl oxygen OB and water hydrogen HW (solid), as well as urea hydrogen HU (dash). (C) The pair radial distribution function g(r) between positively charged lysine side-chain hydrogen HK and water oxygen OW (solid), as well as urea oxygen OU (dash). (D) The pair radial distribution function g(r) between negatively charged glutamic acid side-chain oxygen OE and water hydrogen HW (solid), as well as urea hydrogen HU (dash). All of the g(r) functions are averaged over the first 10 ns (black, green) and the last 10 ns (red, blue) of total 100 ns, respectively.