I have followed with interest the discussions regarding refinement of proteins with ligands. I wonder if Pavel or anybody else could comment on the refinement of proteins with covalently attached ligands. I am currently handling that in CNS as I know how to write the patches. Is this possible in phenix? Coudl it be handled by generating a "new amino acid" like say a Cys with beta mercapto ethanol attached and then get the program to link this "new amino acid" via normal peptide bonds with the rest of the protein? What about a capped N-terminus? can we make the "new amino acid" say N- acetyl-Gly and get the program to put this at the N-terminus? Any help is appreciated. Marcelo ____________________________________________ Marcelo C. Sousa, Ph.D. Department of Chemistry and Biochemistry Cristol Chemistry Building. Room 100 215 UCB University of Colorado at Boulder Boulder, CO 80309 Phone: (303) 735 4341 Fax: (303) 492 5894