Identification of thymidine nucleotidase and deoxyribonucleotidase activities among normal isozymes of 5'-nucleotidase in human erythrocytes.
Proc Natl Acad Sci U S A
; 81(2): 588-92, 1984 Jan.
Article
em En
| MEDLINE
| ID: mdl-6320196
ABSTRACT
The persistence of normal thymidine nucleotidase (ThyNase) activity in subjects with pyrimidine nucleotidase (PyrNase) deficiency suggested the possible existence of separate isozymes in normal human erythrocytes. This hypothesis was confirmed by studies of PyrNase-deficient individuals from five unrelated families. Erythrocytes deficient in PyrNase retained normal activity of an enzyme system preferentially active at pH 6.2 with a variety of 2'-deoxyribonucleoside 5'-monophosphate substrates, including those of uridine, thymidine, and cytidine. Lesser activities were observed with the corresponding ribonucleotides. Normal control hemolysates were also found capable of effectively dephosphorylating purine nucleotides (dAMP greater than AMP) when pH was lowered sufficiently from the pH 7.4-8.0 region commonly used in conventional assays. Variations in substrate specificity, pH optima, kinetics, and sensitivity to inactivation by Pb2+ indicated the existence of multiple 5'-nucleotidase isozymes in normal erythrocytes PyrNase and deoxyribonucleotidase(s) that might function physiologically in the conversion of DNA-derived nucleotides to diffusible nucleosides. Evolution of such a unique 5'-nucleotidase suggests that normal erythroblast maturation and nuclear extrusion is accompanied by a degree of karyolysis sufficient to require dephosphorylation and clearance of DNA degradation products.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Eritrócitos
/
Isoenzimas
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Nucleotidases
Tipo de estudo:
Diagnostic_studies
Limite:
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1984
Tipo de documento:
Article
País de publicação:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA