Plasmepsin
Encyclopedia
Plasmepsins are a class of at least 10 enzymes ( and ) produced by the plasmodium
parasite. There are ten different isoforms of these proteins and ten genes coding them respectively in plasmodium falciparum (Plm I, II, III, IV, V, VI, VII, IX, X and HAP). It has been suggested that the plasmpesin family is smaller in other human plasmodium species. Expression of Plm I, II, IV, V, IX, X and HAP occurs in erythrocytic cycle, and expression of Plm VI, VII, VIII, occurs in exoerythrocytic cycle. Through their haemoglobin-degrading activity, they are an important cause of symptoms in malaria
sufferers. Consequently this family of enzymes is a potential target for antimalarial drugs.the aspartic protease of Plasmodiumspecies are known as Plasmepsins
Plasmepsins are aspartic acid
proteases, which means their active site
contains two aspartic acid
residues. These two aspartic acid
residue act respectively as proton donor and proton acceptor, catalysing the hydrolysis of peptide bond
in proteins.
There are four types of plasmepsins, closely related but varying in the specificity of cleavage site. Plasmepsins I and II cleave hemoglobin
between residues Phenylalanine
33 and Leucine
34 of α-globin subunit.
The name plasmepsin may come from plasmodium (the organism) and pepsin
(a common aspartic acid protease with similar molecular structure).
The closest (non-pathogenic) enzymatic equivalent in humans is the beta-secretase
enzyme.
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
parasite. There are ten different isoforms of these proteins and ten genes coding them respectively in plasmodium falciparum (Plm I, II, III, IV, V, VI, VII, IX, X and HAP). It has been suggested that the plasmpesin family is smaller in other human plasmodium species. Expression of Plm I, II, IV, V, IX, X and HAP occurs in erythrocytic cycle, and expression of Plm VI, VII, VIII, occurs in exoerythrocytic cycle. Through their haemoglobin-degrading activity, they are an important cause of symptoms in malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
sufferers. Consequently this family of enzymes is a potential target for antimalarial drugs.the aspartic protease of Plasmodiumspecies are known as Plasmepsins
Plasmepsins are aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
proteases, which means their active site
Active site
In biology the active site is part of an enzyme where substrates bind and undergo a chemical reaction. The majority of enzymes are proteins but RNA enzymes called ribozymes also exist. The active site of an enzyme is usually found in a cleft or pocket that is lined by amino acid residues that...
contains two aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
residues. These two aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
residue act respectively as proton donor and proton acceptor, catalysing the hydrolysis of peptide bond
Peptide bond
This article is about the peptide link found within biological molecules, such as proteins. A similar article for synthetic molecules is being created...
in proteins.
There are four types of plasmepsins, closely related but varying in the specificity of cleavage site. Plasmepsins I and II cleave hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
between residues Phenylalanine
Phenylalanine
Phenylalanine is an α-amino acid with the formula C6H5CH2CHCOOH. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L-Phenylalanine is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form...
33 and Leucine
Leucine
Leucine is a branched-chain α-amino acid with the chemical formula HO2CCHCH2CH2. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encoded by six codons and is a major component of the subunits in ferritin, astacin and other 'buffer' proteins...
34 of α-globin subunit.
The name plasmepsin may come from plasmodium (the organism) and pepsin
Pepsin
Pepsin is an enzyme whose precursor form is released by the chief cells in the stomach and that degrades food proteins into peptides. It was discovered in 1836 by Theodor Schwann who also coined its name from the Greek word pepsis, meaning digestion...
(a common aspartic acid protease with similar molecular structure).
The closest (non-pathogenic) enzymatic equivalent in humans is the beta-secretase
Beta-secretase
Beta-secretase 1 also known as beta-site APP cleaving enzyme 1 , memapsin-2 , and aspartyl protease 2 is an enzyme that in humans is encoded by the BACE1 gene.β-Secretase is an aspartic-acid protease important in the pathogenesis of Alzheimer's disease,...
enzyme.
External links
- The MEROPSMeropsMerops may refer to:* Merops , a genus of bee-eaters.* MEROPS, an on-line database for peptidases.It may also refer to several figures from Greek mythology:* King of Ethiopia, husband of Clymene, who lay with Helios and bore Phaethon...
online database for peptidases and their inhibitors: Plasmepsin I A01.022, Plasmepsin II A01.023