If you use Darling models, there is no need for tape to fix the peptide bond---the Darling models make quite good non-rotatable peptide planes. They are also excellent for showing hydrogen bonds. What they are *not* good for is showing steric clashes, which I believe was the original goal of the request for tools for teaching about Ramachandran plots. See http://www.soe.ucsc.edu/~karplus/bme205/f05/darling-model/build-peptides.html http://www.soe.ucsc.edu/~karplus/bme205/f05/paper1-darling.html for specific instructional use of the Darling models for teaching about protein backbones. ------------------------------------------------------------ Kevin Karplus karplus at soe.ucsc.edu http://www.soe.ucsc.edu/~karplus Professor of Biomolecular Engineering, University of California, Santa Cruz Undergraduate and Graduate Director, Bioinformatics (Senior member, IEEE) (Board of Directors & Chair of Education Committee, ISCB) life member (LAB, Adventure Cycling, American Youth Hostels) Effective Cycling Instructor #218-ck (lapsed) Affiliations for identification only.