Enzymes are giant biological molecules and are responsible for speeding up chemical reactions in the body. Almost all enzymes are also proteins, these are proteins which are made up of amino acids. Hephaestin is an enzyme of caeruloplasmin, thus part of a plasma protein, which is the most abundant blood protein.
What is hephaestin?
Hephaestin (also called HEPH as a gene) is a homologous enzyme, this means that it has the same phylogenetic origin as other enzymes in the body. It originates from the so-called caeruloplasmin, a membrane protein: these are proteins that are bound to biomembranes, so hephestin is found in new mouths, a superphylum of tissue animals. Moreover, the protein was named by its discoverer, C. D. Vulpe, after the Greek god Hephaistos, which roughly means “blacksmith.” According to Greek mythology, Hephaistos was the god of fire, one of the twelve Olympian deities, and was responsible for all metalworking. Hephaestin is a human protein and has 1136 amino acids. It has a secondary to quaternary structure and is monomeric, meaning that the molecules of the protein are reactive and can join together to form branched polymers, multiple monomers linked together. It also has two isoforms: These are molecules that are identical in composition but different in structure.
Function, effect and tasks for body and health
Hephaestin proteins are found in substantia spongiosa (spongiosa for short). Cancellous bone is a form of bone tissue located inside the bone. The interior of the bone has a spongy consistency and is made up of bone bellicles; their cavity also contains the bone marrow. The cancellous bone in flat bones is called diploë. It is particularly common in the enterocytes of the small intestine, which are cells of the epithelium and form the mucosa of the small intestine, lining the lumen (diameter of a cavity) of the small intestine. Hephaestin is responsible for the transport of iron: The iron is imported to the membrane protein, where it is subsequently oxidized. This means that the iron combines with oxygen, so it prepares the iron for export. It is exported after oxidation to ferroportin, also a membrane protein consisting of 551 amino acids. When iron is oxidized, it converts the iron with two protons into an iron molecule with three protons. Thus, hephestin is an active part in iron metabolism. Iron metabolism is the absorption, distribution and excretion of iron in the human organism. Even the whole energy metabolism in the body is dependent on iron, this makes hephestin as a part of iron metabolism indispensable in the human body. Erythropoietin is responsible for the regulation of hephaestin (also in iron metabolism): it is a protein hormone responsible for the formation of red blood cells. It is also responsible for the expression of hephaestin in the duodenum, a part of the small intestine closest to the stomach.
Formation, occurrence, properties, and optimal levels
The protein hephaestin is found in the breast, intestine, and bone follicles of the human body. It is also found in the so-called fibroblast: These are motile cells found in human connective tissue that become immobile after maturing into fibrocytes. Hephaestin consists of 1136 amino acids, a class of organic compounds that have at least one carboxyl group (COOH-) and one amino group (-NH2). It has a molecular mass of about 130 kDa (dalton): this is a unit of molecular mass and the twelfth part of the mass of a carbon atom. Hephestin further belongs to the homolog family of ferroxidase, also an enzyme that accelerates the oxidation of iron II to iron III. Since hephaestin is an essential part of iron transport in the human body, optimal levels of the membrane protein are dependent on iron levels. A full-grown male adult has about 4240 mg of iron (thus about 4-5 g) in the organism. However, if a person possesses an increased amount of iron, this can be attributed to low activity of hephaestin.
Diseases and disorders
A particularly low activity of hephaestin and thus an increased concentration of iron in the body can lead to diseases such as Parkinson’s disease.Increased cancer stage in intestinal cells can also be attributed to increased iron intake and associated low hephaestin activity. An experiment once showed that rats fed an increased amount of iron had increased expression of caeruloplasmin and ferroportin, but not of hephaestin. Rats that had neither caeruloplasmin nor hephaestin in their organism showed particularly many symptoms of macular degeneration. Macular degeneration is a disease of the retina that particularly affects the yellow spot, an area in the eye specifically located in the central part of the retina. Macular degeneration can lead to a decrease in visual acuity due to a loss of function of the “point of sharpest vision” and, in many, severe cases, to visual impairment and blindness.
