Biomaterial Database

Enhanced carboxyl methylation of membrane-associated hemoglobin in human erythrocytes. 1988

C M O'Connor, and K E Yutzey

Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545.

The alpha- and beta-chains of hemoglobin (Hb) are methylated in intact erythrocytes and in cellular extracts by a protein D-aspartate methyltransferase (EC 2.1.1.77) specific for D-aspartyl and L-isoaspartyl residues. During an 18-h incubation of intact erythrocytes with L-[methyl-3H]methionine, the subfraction of Hb molecules associated with the membrane becomes progressively enriched with methyl esters, reaching a specific activity 10-fold that of cytosolic Hb. The enhanced methylation of membrane Hb in intact cells appears not to result from its methylation at sites with inherently greater stability, since salt-extracted membrane Hb 3H-methyl esters and cytosolic Hb 3H-methyl esters are hydrolyzed at similar rates at pH 8.4 in vitro. Oxidative treatment of column-purified Hb with acetylphenylhydrazine produces an immediate 4-fold increase in its specific methyl-accepting activity coincident with the production of hemichrome forms known to possess a higher affinity for membrane binding sites. Together, the results suggest that the methyltransferase preferentially recognizes partially denatured Hb molecules which possess a higher affinity for membrane binding sites, similar to Hb forms observed in senescent erythrocytes.

UI	MeSH Term	Description	Entries
D008745	Methylation	Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)	Methylations
D010659	Phenylhydrazines	Diazo derivatives of aniline, used as a reagent for sugars, ketones, and aldehydes. (Dorland, 28th ed)
D011496	Protein Methyltransferases	Enzymes that catalyze the methylation of amino acids after their incorporation into a polypeptide chain. S-Adenosyl-L-methionine acts as the methylating agent. EC 2.1.1.	Protein Methylase,Protein Methylases,Protein Methyltransferase,Methylase, Protein,Methylases, Protein,Methyltransferase, Protein,Methyltransferases, Protein
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
D004912	Erythrocytes	Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.	Blood Cells, Red,Blood Corpuscles, Red,Red Blood Cells,Red Blood Corpuscles,Blood Cell, Red,Blood Corpuscle, Red,Erythrocyte,Red Blood Cell,Red Blood Corpuscle
D006454	Hemoglobins	The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.	Eryhem,Ferrous Hemoglobin,Hemoglobin,Hemoglobin, Ferrous
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D026601	Protein D-Aspartate-L-Isoaspartate Methyltransferase	A PROTEIN O-METHYLTRANSFERASE that recognizes and catalyzes the methyl esterification of ISOASPARTIC ACID and D-ASPARTIC ACID residues in peptides and proteins. It initiates the repair of proteins damaged by the spontaneous decomposition of normal L-aspartic acid and L-asparagine residues.	Protein-D-Aspartate Methyltransferase,Protein-L-Isoaspartate-D-Aspartate-O-Methyltransferase,D-Aspartyl-L-Isoaspartyl Methyltransferase,Isoaspartyl-Aspartyl Protein Methyltransferase,L-Isoaspartyl Protein Carboxymethyltransferase,Methyltransferase PIMT,PCMT1 Gene Product,Protein L-Isoaspartate O-Methyltransferase,Protein L-Isoaspartyl Methyltransferase,Protein-D-Asp Methyltransferase,Protein-L-Isoaspartate Methyltransferase,Protein-beta-Aspartate Methyltransferase,pcm Gene Product,Carboxymethyltransferase, L-Isoaspartyl Protein,D Aspartyl L Isoaspartyl Methyltransferase,Gene Product, PCMT1,Gene Product, pcm,Isoaspartyl Aspartyl Protein Methyltransferase,L Isoaspartyl Protein Carboxymethyltransferase,L-Isoaspartate O-Methyltransferase, Protein,L-Isoaspartyl Methyltransferase, Protein,Methyltransferase, D-Aspartyl-L-Isoaspartyl,Methyltransferase, Isoaspartyl-Aspartyl Protein,Methyltransferase, Protein D-Aspartate-L-Isoaspartate,Methyltransferase, Protein L-Isoaspartyl,Methyltransferase, Protein-D-Asp,Methyltransferase, Protein-D-Aspartate,Methyltransferase, Protein-L-Isoaspartate,Methyltransferase, Protein-beta-Aspartate,O-Methyltransferase, Protein L-Isoaspartate,PIMT, Methyltransferase,Protein Carboxymethyltransferase, L-Isoaspartyl,Protein D Asp Methyltransferase,Protein D Aspartate L Isoaspartate Methyltransferase,Protein D Aspartate Methyltransferase,Protein L Isoaspartate D Aspartate O Methyltransferase,Protein L Isoaspartate Methyltransferase,Protein L Isoaspartate O Methyltransferase,Protein L Isoaspartyl Methyltransferase,Protein Methyltransferase, Isoaspartyl-Aspartyl,Protein beta Aspartate Methyltransferase