Hi all, I'm following the procedure reported in a previous message to connect the ends of a peptide. In my case ~ribbon display delete :41@oxt bond :1@n: 41@c After, I run minimization, but I have the following message Charge model: AMBER ff14SB Total charge for #0: 0.810 The following residues had non-integral charges: SER 1.A 0.8102 1 model(s) had non-integral total charge Details in reply log Residue #0:1.A (SER/serine) is missing atom H_1 In my model SER1 has two hydrogens named H2 and H3. Now the nitrogen has four covalent bonds that is unusual. If, before connecting residues 1 and 41, I add hydrogens to the molecule I obtain SER1 with 3 hydrogens. After I remove H2 and H3 and repeat the procedure, in the minimization step I obtain the message that H3 is missing... Any suggestion? Thanks Marco -- Marco Sette, PhD Associate Professor of Molecular Biology Department of Chemical Sciences and Technology The University of Rome, "Tor Vergata" Via della Ricerca Scientifica, 00133, Rome, Italy e-mail:sette@uniroma2.it Tel.: +39-0672594424 Fax: +39-0672594328