Dear Allen, Sue,
we also have had some luck with ACORN, but as our peptide did not have
alpha-helical structure, the postdoc on the project used a 4-aa
beta-turn fragment instead. I can put you in contact with him for more
details. As I understand it, ACORN uses a mixed MR/direct methods
approach.
We had also tried extensive MR before, but without luck - it appears
peptides often are too different for it.
Mark
Quoting [log in to unmask]:
> Have you tried acorn in ccp4? I've had it work well at this resolution,
> especially if the protein/peptide has some alpha helical content. We used
> acorn to solve a small cro protein that we couldn't get molecular replacement
> to work with by using a 5-residue ideal poly-ala helix as the starting model.
>
> Sue
>
> Quoting "Sickmier, Allen" <[log in to unmask]>:
>
>> I am trying to do molecular replacement on a small peptide (less
>> than 40 AA) and have not had any success using phaser. Are there
>> any tricks or better programs for really small peptides?
>> The data is great 1.1 A, ~35% solvent, and two molecules in the
>> ASU. I have tried all the standard stuff, changing resolution cut
>> off etc. I may move to sulfur phasing at this resolution but I
>> would like to get the MR to work.
>>
>>
>> Allen
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