Hi Harry,

Deducing the element from the atom name has always been unreliable so since PDB version 3 you have to get it from columns 77-78. There is no implied element in the atom name anymore.

HTH,
Robbie


On 15 May 2024 12:28, Harry Powell <0000193323b1e616-dmarc-requ...@jiscmail.ac.uk> wrote:

Hi folks

I’m sure that this has been answered many times before (I’m sure that when I was young I even read it here…), and I *know* that we should all be using mmCIF, but I’m using PDB format files generated by a popular Python module and I wanted to check the output against a definitive format definition (if that’s not tautology).

I noticed this because I was encouraged to try Moorhen and found that a HEM (apparently written by this module) did not have the atoms connected with bonds in the display.

I’m particularly interested in metal atoms here, and want to be 100% sure that I’ve found a calcium, say, and not a C-alpha.

Q: Is it necessary to check columns 77-78 if I really want to be sure?

I’ve read the following, but can’t see anything obvious in “official” PDB documentation that what it says here is actually defined anywhere:

> Atom names are composed of an atomic (element) symbol right-justified in columns 13-14, and trailing identifying characters left-justified in columns 15-16. A single-character element symbol should not appear in column 13 unless the atom name has four characters (for example, see Hydrogen Atoms). Many programs simply left-justify all atom names starting in column 13. The difference can be seen clearly in a short segment of hemoglobin (entry 3hhb):
>
> Correct:
> HETATM 1071 FE   HEM A   1       8.128   7.371 -15.022 24.00 16.74          FE
> HETATM 1072  CHA HEM A   1       8.617   7.879 -18.361  6.00 17.74           C
> HETATM 1073  CHB HEM A   1      10.356  10.005 -14.319  6.00 18.92           C
> HETATM 1074  CHC HEM A   1       8.307   6.456 -11.669  6.00 11.00           C
> HETATM 1075  CHD HEM A   1       6.928   4.145 -15.725  6.00 13.25           C
>
> Incorrect:
> HETATM 1071 FE   HEM A   1       8.128   7.371 -15.022 24.00 16.74          FE
> HETATM 1072 CHA  HEM A   1       8.617   7.879 -18.361  6.00 17.74           C
> HETATM 1073 CHB  HEM A   1      10.356  10.005 -14.319  6.00 18.92           C
> HETATM 1074 CHC  HEM A   1       8.307   6.456 -11.669  6.00 11.00           C
> HETATM 1075 CHD  HEM A   1       6.928   4.145 -15.725  6.00 13.25           C

I’m sure that someone here will say “why don’t you look at *****, it’s obvious”, in which case - many thanks!

help

Harry

########################################################################

To unsubscribe from the CCP4BB list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1

This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/




To unsubscribe from the CCP4BB list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1

Reply via email to