If they are short then you can create links between amino acids and use them. Please have a look tutorials for jligand:
http://www.ysbl.york.ac.uk/mxstat/JLigand/ You need only one link and declare it between peptides. I think buster, phenix and refmac use same type of dictionaries. All they may be able to handle these links. I think in shelxl you need to define all bonds, there may be a program to help to design them, but I am not qualified to give any recommendation on that. If you have long beta-peptides then adding a lot of links might be tedious. Then we need to modify our programs (in our case refmac) to handle these links automatically. If you have any question or need help to defining links and using them within ccp4 then please let me know. regards Garib On 21 Apr 2012, at 23:34, Richard Baxter wrote: > Dear All, > > Looking to refine a beta-peptide structure (<2 A resolution). Any advice on > use of Refmac, Phenix, SHELX for this, are they in the dicionary? Thanks a > lot. > > Richard > > -- > Asst. Prof. in Chemistry > ===== > Yale University > PO Box 208107 > New Haven, CT 06520-8107 > Tel: +1 203 432 9576 > Fax: +1 203 432 6144 > www.baxterlab.org > ===== Dr Garib N Murshudov Group Leader, MRC Laboratory of Molecular Biology Hills Road Cambridge CB2 0QH UK Email: ga...@mrc-lmb.cam.ac.uk Web http://www.mrc-lmb.cam.ac.uk