Document Detail

Increased 5-phospho-alpha-D-ribose-1-diphosphate synthetase (ribosephosphate pyrophosphokinase, EC activity in rat hepatomas.
MedLine Citation:
PMID:  6091867     Owner:  NLM     Status:  MEDLINE    
The behavior of the activity of 5-phosphoribosyl 1-pyrophosphate (PRPP) synthetase (ribosephosphate pyrophosphokinase, EC was elucidated in normal rat liver, in 11 hepatomas of different growth rates, and in rapidly growing differentiating and regenerating liver. Tissue extracts were prepared by centrifugation of 10% homogenates at 100,000 X g for 30 min, and enzyme activity was measured in the protein fractions obtained by 40 and 47% ammonium sulfate saturation of the supernatant fluids from livers and hepatomas, respectively. In the tissue extracts, there was no interfering enzyme activity that utilized PRPP under the standard assay conditions. The affinity of PRPP synthetase for its substrates, ribose 5-phosphate and adenosine triphosphate (ATP), and to Mg2+ was similar in liver and hepatoma extracts. The Km for ribose 5-phosphate was 0.3 mM; for ATP, it was 0.1 mM in the presence of excess Mg2+. The Km for Mg2+ ATP was 1.2 mM in the presence of excess ATP. There was no difference in the affinity of the enzyme for its activators, Mg2+ and inorganic phosphate, in liver and hepatoma preparations; the Km for Mg2+ was 0.6 mM in the presence of excess ATP; the Km for inorganic phosphate was 14.0 mM. The requirement of hepatoma extracts for full phosphate saturation was higher than that of liver extracts (85 versus 65 mM). A standard assay was worked out for the liver and hepatoma systems; in liver, the enzyme activity was linear for 30 min incubation, and in hepatoma it was linear for 15 min incubation. PRPP synthetase activity was proportionate with amounts of protein added over a range of 0.4 to 3.0 mg in both liver and hepatoma extracts. In the liver of normal adult Wistar rats, PRPP synthetase activity was 108 +/- 10 nmol/hr/mg protein. In rat tissues of high cell renewal activity, thymus, testis, spleen, and small intestine, synthetase specific activity was 3.7-, 3.6-, 1.2-, and 1.3-fold higher than that of normal liver. The synthetase specific activity in hepatomas of slow growth rate increased 1.2- to 1.5-fold, and in intermediate and rapidly growing hepatomas it was elevated 1.9- to 4.1-fold higher than that of normal liver.(ABSTRACT TRUNCATED AT 400 WORDS)
J M Baló-Banga; G Weber
Related Documents :
1894437 - Studies on alanine aminotransferase in nematodes.
1352447 - Differences in 2-oxoglutarate dehydrogenase regulation in liver and kidney.
8214587 - An improvement in the pyruvate dehydrogenase complex assay: a high-yield method for pur...
1921327 - Population distribution profiles of the activities of blood alanine and aspartate amino...
3421927 - Preliminary characterization of the multiple forms of ram sperm hyaluronidase.
11240197 - Ph dependent conformational and structural changes of xylanase from an alkalophilic the...
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cancer research     Volume:  44     ISSN:  0008-5472     ISO Abbreviation:  Cancer Res.     Publication Date:  1984 Nov 
Date Detail:
Created Date:  1984-11-28     Completed Date:  1984-11-28     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2984705R     Medline TA:  Cancer Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  5004-9     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Adenosine Triphosphate / metabolism
Cell Line
Liver / enzymology*
Liver Neoplasms, Experimental / enzymology*
Magnesium / pharmacology
Phosphates / pharmacology
Phosphotransferases / metabolism*
Rats, Inbred ACI
Rats, Inbred BUF
Ribose-Phosphate Pyrophosphokinase / isolation & purification,  metabolism*
Tissue Distribution
Grant Support
Reg. No./Substance:
0/Phosphates; 56-65-5/Adenosine Triphosphate; 7439-95-4/Magnesium; EC 2.7.-/Phosphotransferases; EC Pyrophosphokinase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Effect of phorbol esters on iron uptake in human hematopoietic cell lines.
Next Document:  Correlation of asbestos-induced cytogenetic effects with cell transformation of Syrian hamster embry...