Glycosylation In Erythropoietin And Its Uses Biology Essay
The pharmacodynamics and pharmacokinetic belongingss of good glycoproteins can be altered utilizing glycosylation.
Glycosylation is a procedure in which glycosyl groups are added to a protein ensuing in the formation of glycoprotein. There is an addition in solubility of protein and thermodynamic stableness due to glycosylation and it is besides a common station translational alteration ( 2 ) .N and O- linked are the two types of glycosylation. N linked glycosylation onslaughts the Asn site of the consensus sequence of Asn-X-Ser whereas O-linked glycosylation attacks the Ser site ( 3 ) .There are many illustrations of glycoproteins such as erythropoietin. Kidney is the chief unit which is responsible for the synthesis of erythropoietin. Erythropoietin is a protein which is to a great extent glycosylated.
Erythropoietin consequences in activation of erythropoiesis by its action on erythroid primogenitor cell ( 5 ) .Structurally 40 % saccharide is present in erythropoietin. These saccharides are necessary for assorted belongingss like pharmacokinetics, stableness, antigenicity ( 4 ) .Activated human erythropoietin is composed of 3 N-glycosylation sites at Asn 24, Asn 38, Asn 83 and one O-glycosylation sites at Ser 126 in the individual polypeptide concatenation of 165 aminic acids ( 4 ) .
For the biological activity of erythropoietin glycosylation is necessary. The pharmacodynamics and the velocity of katabolism depends upon the figure of sialic acid residues and the agreement of N-linked oligosaccharides.
HOSTS REQUIRED FOR THE PRODUCTION OF ERYTHROPOIETIN:
For the production of recombinant erythropoietin the common hosts are Chinese hamster ovary ( CHO ) and baby hamster kidney ( BHK ) cells. Three types of recombinant human erythropoietin are available, they are epoetin alpha, epoetin beta and epoetin Z. CHO cells are used for the synthesis of epoetin alpha and beta.
BHK cells are used for the synthesis of epoetin Z ( 4 ) . The three major advantages of CHO cells are:Addition in the output of erythropoietin.Its capableness to bring forth oligosaccharide concatenation constructions.These cells die by mortification and are non apoptotic.For the production of erythropoietin it is favourable to take non apoptotic cells. In recombinant CHO cells there is an addition in erythropoietin production and longer life span of the civilization when the optimal pH is maintained. The optimal pH is adjusted by the add-on of Na lactate in the medium which consequences in lessening in the production of lactate ( 6 ) . Addition of 40Mm Na lactate increases the life span of the civilization by 187h and there was a 2.
7 crease additions in the concentration of erythropoietin ( 6 ) . In mammalian cells lactate is a waste compound formed by glycolysis. Collection of lactate causes addition in the sourness of the medium which leads to take down pH and hence apprehensions cell growing.
Hence to cut down the toxicity of lactate Na lactate is added in the medium which consequences in the activation of lactate dehydrogenase ensuing in the transition of lactate to pyruvate. ( 6 )BHK cells are cultured at increased measure on microcarriers captured by Ca alginate gel atoms for the production of recombinant human erythropoietin. The microcarriers and the available infinites in the alginate gel atoms are used up for the proliferation of the BHK cells. Immobilization of the alginate gel and microcarriers are advantageous for high denseness cultivation of these cells and increased productiveness of erythropoietin.
GLYCOSYLATION ANALOGS OF ERYTHROPOIETIN:
1 ) Carbamylated erythropoietin: There are eight lysine residues in the mature erythropoietin molecule. Nine primary amino groups are provided by the N-terminal alanine which is required for carbamylation which consequences in the formation of a molecule called as carbamylated erythropoietin ( CEPO ) . The carbamylation procedure begins with the parent recombinant human erythropoietin molecule.
This chemical reaction is controlled in the being of K cyanate. This reaction consequences in the transition of lysine residues to homoitrulline. Hence carbamylation procedure is used to modify eight lysine residues and N-terminal amino acid for the formation of CEPO ( 13 ) . It is used in the intervention of acute ischaemic shot.2 ) Darbepoetin alpha: It constitutes of two auxiliary N-linked saccharides, three fold addition in the half life of the serum and an higher in vivo activity. It is a hyper glycosylated erythropoietin.
It is used to handle anaemias caused by malignant neoplastic disease during chemotherapy intervention and upsets related to kidney. ( 14 )
1 ) Erythropoietin IN INHERITED RETINAL DEGENERATION.A group of familial retinal devolution is retinitis pigmentosa which is induced by mutant in over 190 cistrons. Preipherin/rds is one of the factor doing retinitis pigmentosa and it encodes a structural protein placed at the terminal of the photoreceptor outer section phonograph record ( 7 ) . Inherited retinal devolution has a common degenerative mechanism in which programmed cell death of the photoreceptor consequences in loss of vision. Erythropoietin and its receptor were repoted to be present in some non haematopoietic tissues which besides includes the oculus. Apoptosis is blocked in legion theoretical accounts of neural cell decease.
When erythropoietin is administered straight into the oculus, it arrests the decease of retinal ganglion cells, it safeguards the photoreceptors from exposure oxidative emphasis evoked cell decease. All signifiers of erythropoietin such as hyperglycosylated erythropoietin and deglycosylated erythropoietin protects the nerve cells of the photoreceptors in the retinal devolution slow mouse ( 7 ) . Erythropoietin prevents cell decease of the nerve cells related with ague or chronic hurts. Systemically administered erythropoietin which is able to traverse the blood retina boundary protects the retina from familial devolution and light harm, hurt caused due to obstructor in the blood vass. ( 8 )2 ) Erythropoietin IN MANAGEMENT OF ANEMIA.Erythropoietin is used in handling anaemia in patients with chronic nephritic failure.
This has well changed clinical pattern in the scientific discipline that trades with upsets related to kidney. The necessity of blood transfusion has decreased due to extended usage of recombinant erythropoietin. In the bone marrow erythropoietin binds to its receptor. There is an initiation of intracellular signaling cascade on binding of the receptor which consequences in written text of anti-apoptotic cistrons. ( 9 ) Hence there is synthesis of ruddy blood cells which consequences in betterment of anaemia. It has besides improved the quality of life in dialysis patients and it has besides improved left ventricular hypertrophy. Epoetin alpha a type of recombinant erythropoietin dainties anemia by picturing the action of the erythropoietin endocrine.
Erythropoietin therapy is good to patients enduring from chronic kidney disease, anaemia caused by AIDS, legion hematologic upsets. ( 10 )ERYTHROPOIETIN MOLECULES TO TREAT ACUTE ISCHEMIC STROKE.Ischemic shot is a important cause of disablement and decease. Several neuroprotective drugs have failed in presymptomatic tests. For the intervention of assorted ague and chronic neurological upsets erythropoietin has been reported to be an effectual drug. Erythropoietin molecules have been reported to possess neuroprotective belongingss which are used in intervention of acute ischaemic shot ( 11 ) .
Erythropoietin intervention consequences in addition in the degree of go arounding erythropoietin and it besides improves the map of the nerve cells and the clinical effect in patients after acute ischaemic shot ( 12 ) . An EPO parallel CEPO is used for bettering the safety and pharmacokinetic belongingss of the clinical test for the intervention of acute ischaemic shot.
Glycosylation in erythropoietin is of import for intervention of assorted ague and chronic upsets of kidney. It besides consequences in structural change of the erythropoietin ensuing in the formation of assorted parallels recombinant erythropoietin that are used for many curative intents.