Isozymes of human erythrocyte pyrimidine 5'-nucleotidase--chromatographic separation and their properties.
The biochemical properties of two isozymes of human erythrocyte pyrimidine 5'-nucleotidase (P5N) separated by ion-exchange chromatography were studied. These two isozymes, P5N-I and P5N-IIB, can be distinguished from each other by substrate specificity, pH dependent activity and thermostability. P5N-I is thermolabile and dephosphorylates various pyrimidine 5'-monophosphates optimally around pH 7. UMP and CMP were found to be most effective substrates. P5N-IIB is thermostable and characterized by its high Michaelis constant and maximum velocity for dUMP or dTMP and acidic pH optima. The molecular weight was estimated to be 39,000 for P5N-I and 44,000 for P5N-IIB by gel filtration. These data suggest that these two isozymes are independent proteins and probably encoded by distinct structural gene loci.
Hirono
A
A
Fujii
H
H
Miwa
S
S
D015720:5'-Nucleotidase; D002852:Chromatography, Ion Exchange; D004912:Erythrocytes / Q000201:enzymology*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009708:Nucleotidases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011742:Pyrimidine Nucleotides / Q000378:metabolism; D013379:Substrate Specificity
D007527:Isoenzymes; D011742:Pyrimidine Nucleotides; D009708:Nucleotidases; D015720:5'-Nucleotidase