[Study of the interaction of proflavine and isomeric diribonucleoside monophosphates CpG and GpC by proton magnetic resonance]

A comparative study of the interaction of proflavine with isomeric diribonucleoside monophosphates CpG and GpC has been made by the method of 1H NMR (270 MHz). A method of calculation of the parameters of complex formation from the concentration dependences of proton chemical shifts of the dye has been proposed. The equilibrium constants of 1:1 and 1:2 complexes association of these molecules and the most probable structures of the complexes have been determined.

The additional guanylate at the 5' terminus of Escherichia coli tRNAHis is the result of unusual processing by RNase P

In eucaryotes the 5'-terminal guanylate moiety of mature tRNAHis is added posttranscriptionally. To determine whether the same mechanism occurs in procaryotes, we processed in vitro-derived Escherichia coli tRNAHis precursors to mature tRNA, either in E. coli extracts or by using pure M1-RNA, the catalytic component of RNase P. The results show that the extra guanylate at the 5' end of mature E. coli tRNAHis is encoded in the gene and is found in tRNA as the result of an unusual cleavage by RNase P.

On the presence of guanosine phosphate in the tail of bacteriophage T4

Treatment of gp18, a biologically active monomer of the structural protein of the bacteriophage T4 contractile sheath, with 0.6 M-HClO4 leads to the release of GDP, GMP and inorganic phosphate. Each gp18 molecule is shown to carry three atoms of phosphorus. In the isolated protein preparation, gp18 and the nucleoside phosphate are in equimolar relation. It is suggested that in the native sheath-protein subunit, GDP and inorganic phosphate are united as GTP.

Simultaneous determination of guanine nucleotides in rat brain by high-performance liquid chromatography with dual-electrochemical detection

A new, sensitive, and specific assay method for guanine nucleotides using high-performance liquid chromatography with dual-electrochemical detection was developed. GTP, GDP, GMP, and cyclic GMP were separated with reversed-phase "ion-pair" chromatography and detected by a dual-electrochemical detector. Only guanine nucleotides among all purine and pyrimidine nucleotides responded to the electrochemical detector at 0.95 V. The peak heights for these guanine nucleotides were linear at concentrations between 0.5 pmol and 1 nmol. The regional distribution of these guanine nucleotides in the rat brain was studied by this new assay method.

High-performance liquid chromatographic investigations on the time-dependent reaction of cis-Pt(NH3)2Cl2, Pt(en)Cl2 and Pt(pn)Cl2 with RNA fragments

The reaction of three platinum compounds, Pt(NH3)2Cl2, Pt(en)Cl2 and Pt(pn)Cl2 with nucleic acid fragments (Ade, Gua; GpG, GpA and ApA), both reactants (1:1, 1 X 10(-2) M; 1 X 10(-3) M) being dissolved in water, has been studied. UV measurements have been used to characterize the products. Kinetics and adduct formation in the nucleoside-Pt compound system were studied by reversed-phase high-performance liquid chromatography [gradient 0-30% methanol in 30 min, ammonium acetate buffer (0.1 M) at pH 4.25] at fixed intervals of time and the product formation was examined by measuring the peak heights. After 10 h, the reaction was complete for guanosine and showed a steady state for adenosine. The increasing lipophilicity in the sequence of the platinum compounds resulted in a shift to longer retention times.

Fluorescence decay studies of the DNA-3,6-diaminoacridine complexes

The interaction of several 3,6-diaminoacridines with DNAs of various base composition has been studied by steady-state and transient fluorescence measurements. The acridine dyes employed are of the following two classes: class I - proflavine, acriflavine and 10-benzyl proflavine; class II - acridine yellow, 10-methyl acridine yellow and benzoflavine. It is found that the fluorescence decay kinetics follows a single-exponential decay law for free dye and the poly[d(A-T)]-dye complex, while that of the dye bound to DNA obeys a two-exponential decay law. The long lifetime (tau 1) for each complex is almost the same as the lifetime for the poly[d(A-T)]-dye complex, and the amplitude alpha 1 decreases with increasing GC content of DNA. The fluorescence quantum yields (phi F) of dye upon binding to DNA decrease with increasing GC content; the phi F values for class I are nearly zero when bound to poly(dG) X poly(dC), but those for class II are not zero. This is in harmony with the finding that GMP almost completely quenches the fluorescence for class I, whereas a weak fluorescence arises from the GMP-dye complex for class II. The fluorescence spectra of the DNA-dye complexes gradually shift toward longer wavelengths with increasing GC content. In this connection, the fluorescence decay parameters show a dependence on the emission wavelength; alpha 1 decreases with an increase in the emission wavelength. In view of these results, it is proposed that the decay behavior of the DNA-dye complexes has its origin in the heterogeneity of the emitting sites; the long lifetime tau 1 results from the dye bound to AT-AT sites, while the short lifetime tau 2 is attributable to the dye bound in the vicinity of GC pairs. Since GC pairs almost completely quench the fluorescence for class I, partly intercalated or externally bound dye molecules may play an important role in the component tau 2.

[Quantitative analysis of a tetraribonucleotide mixture by ultraviolet spectrophotometry]

Using the least squares method we have calculated the proportions of each nucleotide of a mixture of AMP, CMP, GMP and UMP, after measuring the absorbance of the mixture every ten nanometers from 230 to 290 nm at pH 12.7 and 2. The method is very simple and rapid (the calculations are made in less than one minute), does not require a highly sensitive spectrophotometer to obtain reasonably precise results and, in contrast to the other methods of the literature, it can be applied to quantities as little as 50 micrograms of nucleotides.

Acid-soluble nucleotides of human milk at different stages of lactation

The acid-soluble ribonucleotides of human milk were measured by enzymic and ion-exchange chromatographic procedures at different stages of lactation. Human colostrum and milk contained CMP, AMP, GMP, UMP, GDP-mannose, UDP-N-acetyl-glucosamine, UDP-N-acetyl-galactosamine, UDP-glucose, UDP-galactose, UDP and other minor nucleotides. Cytidine and adenosine derivatives were present in relatively higher amounts than in milk from ruminant species. The nucleotide concentration decreased with advancing lactation. Human milk at 3 months of lactation contained about 10 mumol/100 ml nucleotides, which represented about 75% of the amount of nucleotides present in human colostrum. Human milk did not contain orotic acid. The UDP-glucose/UDP-galactose ratio was constant during lactation and was similar to that of milks from ruminant species.

2' and 3' ribonucleoside monophosphate in leukocytes of acute myeloid leukemia: markers for early diagnosis of relapse

Levels of 2' and 3' purine and pyrimidine ribonucleoside monophosphates (2'-, 3'-NMP) in leukocytes from blood and/or bone marrow were measured in three adult patients with acute non-lymphoblastic leukemias. The measurements of 2'-, 3'-NMP were made by high-performance liquid chromatography (HPLC) at various times in the course of the disease. Complete remission (CR) was obtained for all three patients but two of these have since died after relapsing at 8 and 9 months, respectively. The third patient remains in CR at 1 1/2 year. The levels of 2'-, 3'-NMP in the leukocytes of the patient remaining in remission have not changed since the beginning of his remission. However, in the patients who relapsed 2'- and 3'-NMP levels increased first in bone marrow than in blood leukocytes. These increases occurred about 3 months before the relapse was detected by morphological criteria. These data suggest that 2'-, 3'-NMP measurements may have a prognostic value if used to monitor patients with acute myeloid leukemia in CR.

Transcriptional initiation and 5' termini of yeast mitochondrial RNA

We have used vaccinia virus guanylyltransferase to label polyphosphate-terminated yeast mitochondrial RNAs in vitro with [alpha-32P]GTP. Hybridization of RNA labeled in vitro indicates the presence of multiple transcriptional initiation sites in both grande and petite mitochondrial genomes. Agarose/urea gel electrophoresis of capped RNA suggests the existence of a precursor to the small (14 S) rRNA. In contrast, direct examination of the large (21 S) rRNA by partial ribonuclease T1 digestion reveals a complete lack of processing of the 5' end of the primary transcript of this RNA.

18O-Labeling of guanosine monophosphate upon hydrolysis of cyclic guanosine 3':5'-monophosphate by phosphodiesterase

The hydrolysis of cGMP by phosphodiesterase was conducted in [18O]water to determine the site of bond cleavage and the stoichiometry of 18O incorporation into 5'-GMP. Three different forms of phosphodiesterase including a calmodulin-calcium-dependent enzyme in its basal and activated states were examined. The hydrolysis of cGMP catalyzed by each of the forms of phosphodiesterase proceeded with incorporation of 1 18O atom recoverable in the phosphate moiety of each molecule of 5'-GMP generated. No molecular species of phosphate deriving from the 5'-GMP generated containing two or three 18O were detectable. These results indicate that the phosphodiesterase-catalyzed hydrolysis of cGMP proceeds by nucleophilic substitution at phosphorus resulting in P-O bond cleavage. The stoichiometry of 18O incorporation indicates that the reaction proceeds without phosphate-water oxygen exchange when the hydrolytic reaction is catalyzed by diverse forms of phosphodiesterase in the basal or activated state. These considerations of the phosphodiesterase reaction help to establish the validity of monitoring the rate of enzyme-catalyzed hydrolysis of cGMP as a function of the rate of 18O-labeling of the phosphate of 5'-GMP when the reaction proceeds in a medium of predetermined 18O enrichment.

Effect of sensitization on spontaneous and phosphatidylserine-induced histamine release and on cyclic AMP and GMP levels in isolated rat mast cells

Sprague Dawley rats were sensitized with 20 microgram or 100 mg egg albumin (using pertussis vaccine as adjuvant). Mast cells isolated from the former group of animals showed a higher degree of histamine release upon challenge in vitro with egg albumin than those from the latter group. Using the lower amount of antigen for immunization mast cells from Hooded Lister rats showed an even higher degree of histamine release induced by antigen. An increased antigen-induced histamine release was associated with an increased spontaneous and phosphatidylserine-induced histamine release. Histamine release induced by phosphatidylserine was found to be specific in so far as it was calcium dependent and theophylline-inhibited. The basal level of cyclic AMP in mast cells was significantly depressed by sensitization. There was a relationship between the cyclic AMP/cyclic GMP ratio and the degree of spontaneous, phosphatidylserine-induced and anaphylactic histamine release. The results suggest that sensitization induces an increased release of histamine not only to the specific antigenic stimulus but also to more unspecific stimuli. Concomitantly there is a fall in the cyclic AMP/cyclic GMP ratio. The relationship between these two phenomena is discussed.

Caffeine, cyclic nucleotides, and breast disease

Methylxanthine consumption is associated with the development of fibrocystic disease of the breast. Methylxanthine abstention is associated with resolution of signs and symptoms of fibrocystic disease. Abstinence from methylxanthine consumption decreased breast biopsies and the need for major breast surgery because of benign disease. Methylxanthine consumption is associated with elevated cyclic adenosine monophosphate (AMP) and cyclic guanosine monophosphate (GMP) values in fibrocystic dsiease over those obtained in normal breast tissue.