Two major isozymes of the protein D-aspartyl/L-isoaspartyl methyltransferase from human erythrocytes. 1988

I M Ota, and J M Gilbert, and S Clarke
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.

We have been able to separate protein carboxyl methyltransferase activity from human erythrocyte cytosol into two major fractions by DEAE-cellulose chromatography. These isozymes, designated I and II, are characterized by their isoelectric points of approximately 6.6 and 5.5 as determined by isoelectric focusing in polyacrylamide gels. The ratio of the isozymes (II/I) was found to range from 0.52 to 1.2 in blood samples from 14 individuals. We did not detect differences in this ratio between males and females. We also found no differences between freshly drawn and outdated blood samples. Both isozymes catalyzed the methylation of proteins such as ovalbumin as well as synthetic L-isoaspartyl-containing peptides.

UI MeSH Term Description Entries
D007525 Isoelectric Focusing Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point. Electrofocusing,Focusing, Isoelectric
D007526 Isoelectric Point The pH in solutions of proteins and related compounds at which the dipolar ions are at a maximum. Isoelectric Points,Point, Isoelectric,Points, Isoelectric
D007527 Isoenzymes Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics. Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D008297 Male Males
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
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
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
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
D005260 Female Females

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