Dear ChimeraX users! I am using the following command to calculate and save in the log information regarding hydrogen bonds based on the consideration of multi-frame pdb of the complex # calculate hydrogen bonds for the first 14 frames of pdb hbonds #1.1-14}&protein restrict #1.1-14}&ligand coordsets false interModel false makePseudobonds false log true intraRes false saveFile log.txt which gives me something like this: structure_name: 18 H-bonds H-bonds (donor, acceptor, hydrogen, D..A dist, D-H..A dist): #1.1/? ASN 142 ND2 #1.1/A UNL 1 N #1.1/? ASN 142 2HD2 3.313 2.522 #1.1/? SER 144 N #1.1/A UNL 1 O #1.1/? SER 144 H 2.953 2.224 #1.1/A UNL 1 O #1.1/? LEU 141 O #1.1/A UNL 1 H 2.753 1.877 #1.2/? ASN 142 ND2 #1.2/A UNL 1 N #1.2/? ASN 142 2HD2 3.240 2.429 #1.2/A UNL 1 O #1.2/? HIS 163 NE2 #1.2/A UNL 1 H 3.317 2.389 #1.3/? SER 144 N #1.3/A UNL 1 O #1.3/? SER 144 H 3.005 2.272 #1.3/A UNL 1 O #1.3/? LEU 141 O #1.3/A UNL 1 H 2.738 2.098 #1.3/A UNL 1 O #1.3/? SER 144 OG #1.3/A UNL 1 H 3.054 2.250 #1.6/A UNL 1 O #1.6/? HIS 163 NE2 #1.6/A UNL 1 H 3.172 2.528 #1.7/? CYS 145 SG #1.7/A UNL 1 O #1.7/? CYS 145 HG 3.828 2.949 #1.7/A UNL 1 O #1.7/? LEU 141 O #1.7/A UNL 1 H 3.201 2.393 #1.8/? GLY 143 N #1.8/A UNL 1 O #1.8/? GLY 143 H 3.060 2.238 #1.8/? HIS 163 NE2 #1.8/A UNL 1 O no hydrogen 3.084 N/A #1.9/? GLN 189 NE2 #1.9/A UNL 1 O #1.9/? GLN 189 1HE2 3.148 2.139 #1.10/? GLN 189 NE2 #1.10/A UNL 1 O #1.10/? GLN 189 1HE2 2.941 2.289 #1.10/A UNL 1 O #1.10/? GLN 189 OE1 #1.10/A UNL 1 H 2.985 2.213 #1.11/? GLN 189 NE2 #1.11/A UNL 1 O #1.11/? GLN 189 1HE2 2.803 1.910 #1.14/? ASN 142 ND2 #1.14/A UNL 1 O #1.14/? ASN 142 2HD2 3.199 2.369 ----------------------------------------------------------------------------- I noticed that in the log there is always information regarding interactions between the ligand and the side chains of the protein but nothing regarding hydrogen bonds involved backbone of the protein (Which is confirmed by X-ray data for my complex). for the test I used py@ol to visualise h-bonds and may see in the 12th frame the hydrogen bond involved backbone of the protein.. How could I modify my script to consider additional hydrogen bonds involving backbone atoms ? Thank you very much in advance! Cheers Enrico