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Titolo:
URACIL PHOSPHORIBOSYLTRANSFERASE FROM THE EXTREME THERMOACIDOPHILIC ARCHAEBACTERIUM SULFOLOBUS-SHIBATAE IS AN ALLOSTERIC ENZYME, ACTIVATED BY GTP AND INHIBITED BY CTP
Autore:
LINDE L; JENSEN KF;
Indirizzi:
UNIV COPENHAGEN,INST MOL BIOL,CTR ENZYME RES,SOLVGADE 83H DK-1307 COPENHAGEN DENMARK UNIV COPENHAGEN,INST MOL BIOL,CTR ENZYME RES DK-1307 COPENHAGEN DENMARK
Titolo Testata:
Biochimica et biophysica acta. Protein structure and molecular enzymology
fascicolo: 1, volume: 1296, anno: 1996,
pagine: 16 - 22
SICI:
0167-4838(1996)1296:1<16:UPFTET>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
ESCHERICHIA-COLI; ASPARTATE CARBAMOYLTRANSFERASE; PYRIMIDINE METABOLISM; CRYSTAL-STRUCTURES; PURIFICATION; ACIDOCALDARIUS; RESOLUTION; ATP; PH;
Keywords:
PYRIMIDINE NUCLEOTIDE BIOSYNTHESIS; PYRIMIDINE SALVAGE; THERMOSTABILITY; ALLOSTERIC ENZYME; PHOSPHORIBOSYL PYROPHOSPHATE; (S-SHIBATAE); (ESCHERICHIA-COLI);
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
25
Recensione:
Indirizzi per estratti:
Citazione:
L. Linde e K.F. Jensen, "URACIL PHOSPHORIBOSYLTRANSFERASE FROM THE EXTREME THERMOACIDOPHILIC ARCHAEBACTERIUM SULFOLOBUS-SHIBATAE IS AN ALLOSTERIC ENZYME, ACTIVATED BY GTP AND INHIBITED BY CTP", Biochimica et biophysica acta. Protein structure and molecular enzymology, 1296(1), 1996, pp. 16-22

Abstract

Uracil phosphoribosyltransferase, which catalyses the formation of UMP and pyrophosphate from uracil and 5-phosphoribosyl alpha-1-pyrophosphate (PRPP), was partly purified from the extreme thermophilic archaebacterium Sulfolobus shibatae. The enzyme required divalent metal ions for activity and it showed the highest activity at pH 6.4. The specific activity of the enzyme was 50-times higher at 95 degrees C than at 37 degrees C, but the functional half-life was short at 95 degrees C. The activity of uracil phosphoribosyltransferase was strongly activatedby GTP, which increased V-max of the reaction by approximately 20-fold without much effect on K-m for the substrates. The concentration of GTP required for half-maximal activation was about 80 mu M. CTP was a strong inhibitor and acted by raising the concentration of GTP needed for half-maximal activation of the enzyme. We conclude that uracil phosphoribosyltransferase from S. shibatae is an allosteric enzyme which is activated by a purine nucleotide and inhibited by a pyrimidine nucleotide as seen for several enzymes in the pyrimidine nucleotide biosynthetic pathway of Escherichia coil, but not observed before for any phosphoribosyltransferase.

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Documento generato il 19/09/20 alle ore 11:55:38