Haptoglobin/haemopexin

Haptoglobin/haemopexin These proteins bind free haemoglobin/haem, thus protecting delocalised haemoglobin from influences which might otherwise activate the protein or destabilize the haem ring and promote iron release. 

Transferrin is mainly synthesized in the hepatocytes. There are about 20 known variants. Iron is transported by transferrin (approx. 30% of transferrin is saturated with iron). With the help of a membrane receptor, the iron-transferrin complex is taken up and released in the liver cell, where it is immediately bound (because of its toxicity) to ferritin. The liver cells take up iron predominantly from transferrin, to a lesser degree also from haptoglobin, haemopexin, lactoferrin and circulating ferrin. Transferrin, which is mainly formed in the hepatocytes, may also bind and transport, in decreasing order, chromium, copper, manganese, cobalt, cadmium, zinc and nickel. The half-life of transferrin is 1 - 2 hours, which is very short in view of its total blood concentration of 3-4 mg. Approximately 0.4 g ferritin iron is stored in the liver. In the case of transferrin deficiency, its bacteriostatic and fungistatic effects are also reduced. Transferrin without iron saturation is known as apo-transferrin. (31, 66, 67)... 

These are protein-carbohydrate compounds which contain 10-75% of carbohydrate and over 4% of hexosamines (as distinct from glycoproteins which contain from a trace up to 15% carbohydrate and less than 4% of hexosamines). Oroso-mucoid, haptoglobin and haemopexin are examples of muco-proteins. Increased serum mucoprotein levels are found in many inflammatory conditions such as acute infections and rheumatoid arthritis. Mucoproteins can be estimated by selective precipitation using phosphotungstic acid, followed by determination of the protein or carbohydrate content of the precipitate. 

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