help with my p(r) curves,how to get the accurate Dmax?

Interactive and automated data processing tools (PRIMUS, GNOM, AUTORG).
Scattering from simple bodies (BODIES), peak analysis (PEAK), data plotting (SASPLOT) etc.
Post Reply
Active member
Posts: 17
Joined: 2016.09.27 19:06

help with my p(r) curves,how to get the accurate Dmax?

#1 Post by zhuwenkai » 2017.01.15 17:54

Hi.i have got serval SAXS curves of my protein(apo.mutant.complex).I want to know the conformational changes from Dmax value.

Here comes the question,i think the difference between the Dmax value is comparable to the uncertainy of the values(5%-10%).So i

was puzzled about how to determine the Dmax value.Basically, the p(r) curve should go down to zero smoothly. but i think a range of the

value can meet the condition.

the attachment is my saxs profile,Here is the result i got.(protein-106.91Å;mutant-118.61Å;protein-cdc25,111.55Å;protein-peptide,105.09Å)

and the picture is from a paper published in 2013 (PNAS),the p(r) curve doesn't go down to zero smoothly according to their results,so i want to

know your opinion about how to get the accurate Dmax value.
pnas.png (89.17 KiB) Viewed 3133 times
(38.73 KiB) Downloaded 159 times
(38.73 KiB) Downloaded 128 times
(38.74 KiB) Downloaded 122 times
(38.74 KiB) Downloaded 128 times

User avatar
Posts: 686
Joined: 2007.08.03 18:55
Location: EMBL Hamburg, Germany

Re: how to get the accurate Dmax?

#2 Post by AL » 2017.01.16 16:19

It looks like there are aggregates present in your samples, i.e. the data are not from monodisperse solutions. Check Guinier plots - they all go up at smaller angles. On top of that 'protein-peptide.dat' is affected either by interparticle interactions or improper background subtraction.
I.e. the Dmax estimates will be unreliable here.

Post Reply