Biomaterial Database

Allosteric regulation of calf thymus ribonucleotide reductase. 1978

S Eriksson, and L Thelander

Ribonucleotide reductase was purified 3400-fold from calf thymus. The enzyme preparation was essentially free of kinases and phosphatases and therefore allowed a conclusive study of the allosteric regulation of a eukaryotic ribonucleotide reductase to be made for the first time. Comparable maximal activities were obtained for the reduction of all four ribonucleotide substrates in the presence of their optimal stimulatory effectors. These and other results strongly argue for the existence of only one ribonucleotide reductase in mammalian cells. No reduction was observed in the absence of effector. The reduction of CDP and UDP both required ATP, with no stimulatory effect of any other nucleoside triphosphate. The only activator of GDP reduction was dTTP and the only activator of ADP reduction was dGTP. Reduction of the purine ribonucleotides was further stimulated by ATP but only in combination with dTTP or dGTP. The reduction of all four ribonucleotides was strongly inhibited by dATP, the inhibition being partly released by ATP. The data can be integrated into a scheme which links ribonucleotide reduction to DNA synthesis.

UI	MeSH Term	Description	Entries
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D003565	Cytidine Diphosphate	Cytidine 5'-(trihydrogen diphosphate). A cytosine nucleotide containing two phosphate groups esterified to the sugar moiety. Synonyms: CRPP; cytidine pyrophosphate.	CDP,Diphosphate, Cytidine
D003838	Deoxyadenine Nucleotides	Adenine nucleotides which contain deoxyribose as the sugar moiety.	Deoxyadenosine Phosphates,Nucleotides, Deoxyadenine,Phosphates, Deoxyadenosine
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006153	Guanosine Diphosphate	A guanine nucleotide containing two phosphate groups esterified to the sugar moiety.	GDP,Guanosine 5'-Diphosphate,Guanosine 5'-Trihydrogen Diphosphate,5'-Diphosphate, Guanosine,5'-Trihydrogen Diphosphate, Guanosine,Diphosphate, Guanosine,Diphosphate, Guanosine 5'-Trihydrogen,Guanosine 5' Diphosphate,Guanosine 5' Trihydrogen Diphosphate
D000494	Allosteric Regulation	The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.	Regulation, Allosteric,Allosteric Regulations,Regulations, Allosteric
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012264	Ribonucleotide Reductases		Ribonucleotide Reductase,Reductase, Ribonucleotide,Reductases, Ribonucleotide