Las proteínas conjugadas o heteroproteínas son moléculas que presentan una parte proteica (apoproteína) y otra no proteica menor (grupo prostético). Esto las diferencia de las proteínas simples u holoproteínas. Todas son globulares, y se clasifican en función del grupo prostético. Fosfoproteínas Presentan ácido fosfórico y son de carácter ácido. Enzimas. (caseína alfa, beta y gamma). Glucoproteínas Glúcido unido covalentemente a la proteína. Desempeñan funciones enzimáticas, hormonales, de coagulación, etc. Destacan las inmunoglobulinas. Lipoproteínas Lípido más proteína. Abundan en las membranas mitocondriales, en el suero. Por ejemplo los quilomicrones. Nucleoproteínas Ácido nucleico más proteína. Hay dos tipos, los que presentan ácido ribonucleico (ribosomas) o ADN (cromosomas). Cromoproteínas Se caracterizan porque la fracción no proteica presenta coloración debido a la presencia de metales. Destacan los pigmentos respiratorios (hemoglobina), almacenes de oxígeno (mioglobina), proteínas que intervienen en la transferencia de electrones (citocromos, flavoproteínas), pigmentos visuales (rodopsina, iodopsina).

Leer el artículo completo en Wikipedia · CC-BY-SA

A conjugated protein is a protein that functions in interaction with other (non-polypeptide) chemical groups attached by covalent bonding or weak interactions. Many proteins contain only amino acids and no other chemical groups, and they are called simple proteins. However, other kind of proteins yield, on hydrolysis, some other chemical component in addition to amino acids and they are called conjugated proteins. The non-amino part of a conjugated protein is usually called its prosthetic group. Most prosthetic groups are formed from vitamins. Conjugated proteins are classified on the basis of the chemical nature of their prosthetic groups. Some examples of conjugated proteins are lipoproteins, glycoproteins, phosphoproteins, hemoproteins, flavoproteins, metalloproteins, phytochromes, cytochromes, opsins and chromoproteins. Hemoglobin contains the prosthetic group known as heme. Each heme group contains an iron ion (Fe2+) which forms a co-ordinate bond with an oxygen molecule (O2), allowing hemoglobin to transport oxygen through the bloodstream. As each of the four protein subunits of hemoglobin possesses its own prosthetic heme group, each hemoglobin can transport four molecules of oxygen. Glycoproteins are generally the largest and most abundant group of conjugated proteins. They range from glycoproteins in cell surface membranes that constitute the glycocalyx, to important antibodies produced by leukocytes. 's Principles of Biochemistry (4th ed.). New York, New York: W. H. Freeman and Company.

Leer el artículo completo en Wikipedia · CC-BY-SA