Mechanism of copper transport and delivery in mammals: review and recent findings.

Abstract

The distribution of dietary copper after its absorption from the intestinal tract appears to occur in two stages. In the first stage, copper moves from the intestinal mucosa to the liver and kidney, and in the second stage, it moves from the liver to peripheral tissues. Evidence for these two stages of distribution comes from tracing the path of radiocopper after its intraduodenal or intragastric intubation (or direct injection) into rats. Immediately after intraduodenal administration, radioactive tracer is found in the portal blood, where it attaches to albumin, and transcuprein. The involvement of albumin in the initial transport of incoming copper is well documented (Owen, 1965 and 1971; Marceau and Aspin, 1971; Campbell et al., 1981; Gordon et al., 1987), and albumin has long been known to carry a high affinity copper binding site at its N-terminus (Breslow, 1964; Lau and Sarkar, 1971). The Kd for human albumin has been measured as 10-17 M in the absence of amino acids, and 10-22 M in the presence of L-histidine. As it is by far the most abundant plasma protein, albumin can theoretically bind up to about 40 μg Cu per ml of plasma or serum (assuming about 42 mg of albumin per ml). Nevertheless, albumin is normally relatively unsaturated with copper, binding only about 150 ng Cu per ml in normal adult humans, or less than 15% of the total copper in blood plasma.KeywordsAmmonium SulfateVoid VolumeVoid Volume FractionCopper TransportLectin Affinity ChromatographyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.