Ricin A-chain is an N-glucosidase that attacks ribosomal RNA at a highly conserved adenine residue. Our recent crystallographic studies show that not only adenine and formycin, but also pterin-based rings can bind in the active site of ricin. For a better understanding of the means by which ricin recognizes adenine rings, the geometries and interaction energies were calculated for a number of c...

Inflammation and oxidative stress are known to be involved in the pathogenesis of chronic kidney disease in humans, and in chronic renal failure (CRF) in rats. The aim of this work was to study the role of inflammation and oxidative stress in adenine-induced CRF and the effect thereon of the purported nephroprotective agent gum arabic (GA). Rats were divided into four groups and treated for 4 w...

The crystal structure of a DNA duplex dodecamer d(CGCAAAAATGCG) and its complementary strand has been determined at 2.6-A resolution. Although our goal was to deduce the structural features of the static bending of the helical axis exhibited by adenine-tract structures in solution, we conclude that the overall bend of 20 degrees in the direction of the major groove observed here arises from the...

In addition to their action upon adenine, the adenine aminohydrolases of Azofobacfer vinelandii and of Candida ufilis have been found capable of acting upon 6-chloropurine, 6-iodopurine, 6-hydrazinopurine, 2-amino-6-chloropurine, 2,6-diaminopurine, and 7-aminothiazolo[5,4-dlpyrimidine. In each case the enzyme catalyzes the replacement by a hydroxyl group of the substituent on position 6 or on t...

Adenine nucleotides of guinea-pig neocortical tissues were labelled by incubation with [(14)C]adenine and excess of adenine was then removed by superfusion with precursor-free medium. Adenine derivatives released from the tissue during continued superfusion, including a period of electrical stimulation of the tissue, were collected by adsorption and examined after elution and concentration. The...

In response to an external source of adenine, yeast cells repress the expression of purine biosynthesis pathway genes. To identify necessary components of this signalling mechanism, we have isolated mutants that are constitutively active for expression. These mutants were named bra (for bypass of repression by adenine). BRA7 is allelic to FCY2, the gene encoding the purine cytosine permease and...

The radiation-induced biological behavior of adenine (vitamin B4) was investigated in vitro under various conditions, implementing breast cancer cells (MCF-7 line) as a model. In aerated media (46% OH and 54% O2*-) at pH=7.4, adenine at low concentration (2 micromol) acted as an efficient radiation-protecting agent. At higher concentration, however, it inhibited cytostatic properties with regar...

Riboswitches are RNA-based genetic control elements that function via a conformational transition mechanism when a specific target molecule binds to its binding pocket. To facilitate an atomic detail interpretation of experimental investigations on the role of the adenine ligand on the conformational properties and kinetics of folding of the add adenine riboswitch, we performed molecular dynami...

The adenine nucleotide content of the 2-centimeter segments excised from tray-grown corn (Zea mays L., WF9 x Mo17) roots declines for the first hour after excision. Concomitant with the loss of adenine nucleotides is a decline in respiration and a leakage of K(+). With continued washing, these parameters partially or completely recover and increased phosphate influx develops. Increasing the wou...

GRP94, the endoplasmic reticulum paralog of hsp90, has recently been identified as a peptide and adenine nucleotide-binding protein. To determine if adenine nucleotides directly contribute to the regulation of GRP94 peptide binding activity, an in vitro peptide binding assay was developed. Using purified GRP94, we observed specific, saturable, temperature-sensitive binding of the peptide VSV8, ...