Definition

In addition to the amino acid component, the protein-binding molecule also contains non-amino acid substances, the latter being called cofactors, which are combined in a covalent or non-covalent form and are often separated from the biological material as a whole. Simple protein refers to a molecular composition. Except for the polypeptide protein component composed of amino acids, no non-protein component is called a simple protein. Many proteins in nature belong to this category. The binding protein is composed of a simple protein and other compounds. The other compounds to be bound are usually called non-protein parts (prosthetic groups) of the binding protein. Divided into nuclear proteins (including nucleic acids), glycoproteins (including polysaccharides), lipoproteins (containing lipids), phosphoproteins (including phosphoric acid), metalloproteins (containing metals), and chromoproteins (including Pigment) and the like.

Classification

The binding proteins are mainly classified into the following types. Chromatin: A combination of protein and pigment substances, such as hemoglobin. Lecithin: Protein is combined with lecithin, such as fibrin in the blood, yolk phosphoprotein. Lipoprotein: soluble in water, is a combination of fat and protein. Lipoprotein is a tool for the body to transport fat in the body. Including chylomicrons, very low density lipoprotein, low density lipoprotein, high density lipoprotein. Metalloproteins: Proteins bind to metals, such as transferrin, copper-zinc-binding proteins, and many enzymes contain metal ions. Mucin or glycoprotein: A protein containing carbohydrates such as mannose and galactose, and mucus secreted by human cell tissue contains mucin. Nucleoproteins: Proteins bind to nucleic acids, which are found in tissue germs and human glandular tissues.

Glycoprotein

A protein covalently bound to a sugar having a sugar content of less than 4%. The glycosyl group has disaccharides, oligosaccharides and polysaccharides. Glycoproteins are a very complex class of proteins, such as blood glycoproteins, hormone glycoproteins, cell membrane glycoproteins, ovalbumin, and lectins.

Mucoprotein

A protein that binds to an aminopolysaccharide with a sugar content of less than 4%. Generally, it contains β-glucosamine and is bound to one or more of the following sugars: galactose, mannose, rhamnose, glucuronic acid and the like.

Nucleoprotein

A protein that binds to a nucleic acid. Such as: DNA nuclear protein, ribosome, simple plant virus. Nuclear proteins are found in all living organisms, and the cytoplasm and nucleus contain nuclear proteins.

Lipoprotein

A binding protein composed of a protein and a fat or lipid. Lipoproteins are widely present in animals, and lipoproteins in the blood of higher animals include alpha-lipoproteins and beta-lipoproteins. Lipoproteins in the cell membrane affect the permeability of the cell membrane.

Phosphoprotein

A protein covalently bound to phosphoric acid. Phosphoric acid binds to the side chain hydroxyl group of the serine or threonine of the protein and has a dissociable acidic group mainly present in the egg yolk and milk. Such as: casein (casein), pepsin (pepsin).

Metalloprotein

A protein that binds directly to metal ions. For example, ferritin contains Fe2+, nitrogenase contains Mo2+ and Fe2+, carboxypeptidase contains Zn2+, superoxide dismutase contains Cu2+ and Zn2+, and many proteins contain a small amount of metal.

Hemoprotein

A protein that binds to a heme-based heme, whose main function is to participate in respiratory or oxygen transport. Such as: hemoglobin of higher animals, hemocyanin of lower animals, in addition to: chloroplast, catalase, myoglobin and so on.

Flavoprotein
A protein that binds to flavin nucleotides FAD or FMN. Such as: flavin oxygen, D-amino acid oxidase, etc.

Author's Bio: 

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