A large number of enzymes require copper to work properly. In blood, copper is bound to several larger molecules like albumin and ceruloplasmin, but also to smaller molecules including the amino acid histidine.  Copper histidinate, (Cu-His), plays an important role in moving copper to all organs and tissues where it serves an essential biochemical function. It delivers copper to the cell membranes for uptake by a copper specific transporter. Inside the cell, copper is bound to various molecules and guided to the organelles.

One very important intracellular site is the secretory pathway where copper is delivered to enzymes and guided for excretion. A specific transporter, ATP7A is required to move copper inside this site. If the pump is not functioning as it should, many cells will receive insufficient copper, the hallmark of Menkes disease.