About HPX / Hemopexin:
Hemopexin is a glycoprotein found in the blood plasma of humans. With the highest binding affinity of hemes of any plasma protein, HPX is able to prevent hemes from leaving your body through urination. This helps to maintain low toxicity levels in your blood, while also retaining resources that would otherwise be wasted. Also known as beta-1B-glycoprotein, hemopexin is encoded by the HPX gene in humans.
HPX Mechanism
Hemopexin is able to bind with free hemes found in your blood plasma, traveling through your circulatory system until reaching a receptor like CD91, on hepatocytes or macrophages within the spleen, liver, and bone marrow. This process prevents heme's pro-oxidant and pro-inflammatory, while also promoting free heme's detoxification.
Hemopexin Interactions
Hemopexin interacts with free hemes in your blood with the highest affinity of any plasma protein. This interaction occurs with a 2:1 ratio, meaning that every 2 hemopexin molecules in your blood will bind with 1 heme.
HPX Structure
The structure of hemopexin is a complex crystal, with a novel heme-binding site that is formed between two similar four-bladed β-propeller domains and bounded by the interdomain linker. This plasma protein is most commonly found in the liver and will be produced when inflammation occurs within the body.