So by the way, this is the nitrogen. These are carbons, and these blue ones are oxygen atoms. And this orange one is an H ion. So basically, this is the histidine residue and this is the aspartate residue. And at a relatively high PH, so let's say at a normal PH of 7.4, the PH is not low enough to actually add an H plus ion onto this nitrogen. And so this nitrogen will be missing an H plus ion and no bond will be formed between these two groups.