Ceruloplasmin (Cp) is a blue-colored glycoprotein that contains six copper ions per molecule. It is an acute phase protein – concentrations increase in response to inflammation – and also functions as the main copper transport system in the body. Copper is incorporated into the molecule when it is synthesized by heptaocytes, and released when the Cp is catabolized. In addition to copper transport, Cp catalyzes the oxidation of iron, polyamines, catecholamines, and polyphenols.
Structure of Ceruloplasmin
CP is involved in oxidative stress and in the safe handling of oxygen in some metabolic pathways of vertebrates and has been shown to be associated with reproduction. Serum levels of ceruloplasmin have been found to increase during normal pregnancy in some species and it is thought that this increase during gestation protects against oxidative stress associated with pregnancy. In dogs, the increase in serum ceruloplasmin has been coupled to the time of embryonic endometrial implantation and placentation. In 2011, Erin Willis from the Memphis Zoo published evidence that Cp activity could be correlated to pregnancy status in giant pandas1. The activity of urinary ceruloplasmin was higher during the pregnant luteal phase compared to the pseudopregnant luteal phase. In all term pregnancies examined, levels of active ceruloplasmin were elevated the first week of pregnancy and remained elevated until 20-24 days prior to parturition.
Decreased concentrations occur during recessive autosomal hepatolenticular degeneration (Wilson disease). On a pathochemical level, the disease, which is accompanied by reduced ceruloplasmin synthesis, occurs as a consequence of missing Cu2+ incorporation into the molecule due to defective metallothionein. This results in pathological deposits of copper in the liver (with accompanying development of cirrhosis), brain (with neurological symptoms), cornea (Kayser-Fleischer ring), and kidneys (hematuria, proteinuria, aminoaciduria). In homozygous carriers, ceruloplasmin levels are severely depressed. Heterozygous carriers exhibit either no decrease at all or just a mild decrease. As ceruloplasmin is a sensitive acute phase reactant, increases occur during acute and chronic inflammatory processes. Large increases can lead to a green-blue coloration of the sera.
The Arbor Assays Ceruloplasmin Colorimetric Activity kit, K035-H1, is exclusively licensed from Memphis Zoo and is a convenient method to measure the activity of this enzyme in both urine and serum samples.
Ceruloplasmin Activity Kit, K035-H1, Standard Curve
- Willis et al (2011) The Acute Phase Protein Ceruloplasmin as a Non-Invasive Marker of Pseudopregnancy, Pregnancy and Pregnancy Loss in the Giant Panda; PLoS One; 6(7) e21159