7 May
2009
7 May
'09
7:26 p.m.
On Thu, 7 May 2009, Nathaniel Echols wrote:
I think it's very common for these to have negative difference map peaks, because they'll undergo radiation damage very quickly relative to the rest of the protein.
my understanding is that if there was significant absorption, and if the model scattering is uncorrected for f' - which is in-phase with normal scattering f for that atom - Fc will overestimate Fo, thus, Fo-Fc will be negative. the f'' component will be -(pi/2) out of phase with the normal f, and - here is what i don't get - shift the F so its out of phase. but i don't intutitvely understand how that affects the Fo-Fc map. -bryan