Did you read the articles I mentioned? I dont have my masters degree in molecular biology as you'd imagine given that this is a forum dedicated to people who for the most part are mentally and physically disabled. I would need to spend probably 5 years even if I were a molecular biologist just to understand the role of histidine related to maybe one or two forms of copper in the body. I, like most others on this forum am more concerned with results than figuring out why. Take any enzyme in the body and you could either figure out in layman's terms how it functions so that you might proceed, or you could do the actual deep research and come up with 10,000 functions related to this, with another 10,000 for each of them and have spent 10 years withering away. I dont see how that would be effective. What I do know, is that histidine does carry complexes of copper in the body, that many have been detected and the function isn't necessarily clear, that in vitro studies have been somewhat accurate in vivo, I'm assuming you didn't read the literature I passed on, if you want an in vivo replication of copper transport by histidine, there is one through dialysis. If introducing histidine increases the function of copper in the body while decreasing ceruloplasmin, I have to kind of go with that logically to dig deeper into that implication rather than spinning my wheels figuring out at exactly which terminals histidine acts upon, and at what pH it functions etc. If histidine improves copper dependent enzymatic function, I'm only concerned with the why to the extent that I can understand its implication. I'm assuming you are a lot more well educated on molecular biology than I am, so I passed on the studies where I got my information from, you could shed a lot more light on those studies than I can. Also it's histidine as part of an unknown compound through albumin, I believe in the third study I linked this is mentioned and investigated. It's currently not known.