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PubMed2025

High baseline PD-1+ CD8 T Cells and TIGIT+ CD8 T Cells in circulation associated with response to PD-1 blockade in patients with non-small cell lung cancer.

Blockade of PD-1 or its ligand PD-L1 with antibodies revolutionized treatment for stage III and IV non-small cell lung cancer (NSCLC) since FDA approval in 2015. However, resistance to PD-1/PD-L1 blockade remains a challenge, highlighting the need for biomarkers. This study analyzed 36 stage III and IV NSCLC patients, classified as responders or non-responders by iRECIST criteria. Peripheral blood mononuclear cells collected at baseline and post-treatment were examined for surface and intracellular markers via flow cytometry. CITE sequencing of CD8 T cells from three patients and plasma ctDNA analysis from 13 patients was performed using an ultrasensitive barcoding and next-generation sequencing method. Phenotypic analysis of CD8 T cells revealed higher TIGIT and PD-1 expression at baseline in responders compared to non-responders. Long-term responders (> 21 months) exhibited increased TCF-1+PD-1+ CD8 T cell frequencies relative to shorter-term responders (> 15 months) and non-responders. CITE sequencing revealed intrinsic differences in immune regulation pathways between responders and non-responders. Finally, non-responders showed elevated and increasing ctDNA levels post-treatment, correlating with declining TCF-1+PD-1+ CD8 T cells. Our data suggests combining CD8 T cell analysis with ctDNA dynamics could identify promising biomarkers for monitoring clinical response and treatment efficacy to PD-1/PD-L1 blockade in NSCLC.

Humans↗

PubMed2005

Endonuclease-like activity of heme proteins.

Heme proteins, metmyoglobin, methemoglobin, and metcytochrome c showed unusual affinity for double-stranded DNA. Calorimetric studies show that binding of methemoglobin to calf thymus DNA (CTDNA) is weakly endothermic, and the binding constant is 4.9+/-0.7x10(5) M(-1). The Soret absorption bands of the heme proteins remained unchanged, in the presence of excess CTDNA, but a new circular dichroic band appeared at 210 nm. Helix melting studies indicated that the protein-DNA mixture denatures at a lower temperature than the individual components. Thermograms obtained by differential scanning calorimetry of the mixture indicated two distinct transitions, which are comparable to the thermograms obtained for individual components, but there was a reduction in the excess heat capacity. Activation of heme proteins by hydrogen peroxide resulted in the formation of high valent Fe(IV) oxo intermediates, and CTDNA reacted rapidly under these conditions. The rate was first-order in DNA concentration, and this reactivity resulted in DNA strand cleavage. Upon activation with hydrogen peroxide, for example, the heme proteins converted the supercoiled pUC18 DNA into nicked circular and linear DNA. No reaction occurred in the absence of the heme protein, or hydrogen peroxide. These data clearly indicate a novel property of several heme proteins, and this is first report of the endonuclease-like activity of the heme proteins.

Animals↗

PubMed1976

Physical studies on the size and structure of the covalently closed circular chloroplast DNA from higher plants.

The size and structure of the covalently closed circular chloroplast DNAs (ctDNA) from pea, lettuce, and spinach plants, have been studied by analytical ultracentrifugation. The values of so20,w,Na+ of the native and denatured forms of the open and closed circular DNAs from these plants have been determined. The absolute molecular weight of purified closed circular pea ctDNA monomers has been determined by buoyant equilibrium sedimentation to be 89.1 (S.D. +/- 0.7)-10(6). The value of the so20,w,Na+ of open circular pea ctDNA and its molecular weight, in conjunction with corresponding values for other sizes of circular DNA, has been used to derive an empirical relationship between so20,w,Na+ and molecular weight for open circular DNAs. Using this relationship, the molecular weights of lettuce and spinach ctDNAs have been determined to be 98.2 (S.D. +/- 1.5)-10(6) and 97.2 (S.D. +/- 1.5)-10(6), respectively. At pH values 12.7 and 13, closed circular lettuce and pea ctDNAs have been found to exist as mixtures of reversibly and irreversibly denatured closed circular DNAs.

Animals↗

PubMed2005

Synthesis, antibacterial, antifungal activity and interaction of CT-DNA with a new benzimidazole derived Cu(II) complex.

The ligand [C(16)H(10)O(2)N(4)S(2)] L has been synthesized by the condensation reaction of 2-mercaptobenzimidazole and diethyloxalate. The ligand L was allowed to react with bis(ethylenediamine)Cu(II)/Ni(II) complexes to yield [C(20)H(22)N(8)S(2)Cu]Cl(2)1 and [C(20)H(22)N(8)S(2)Ni]Cl(2)2 complexes. The Ni(II) complex was synthesized only to elucidate the structure of the complex. The complexes 1 and 2 were characterized by elemental analyses, IR, NMR, EPR, UV-vis spectroscopy and molar conductance measurements. Both the complexes are ionic in nature and possess square-planar geometry. The binding of the complex 1 to calf thymus DNA was investigated spectrophotometrically. The absorption spectra of complex 1 exhibits a slight red shift with "hyperchromic effect" in presence of CTDNA. Electrochemical analysis and viscosity measurements were also carried out to ascertain the mode of binding. The complex 1 in the absence and in presence of CT DNA in aqueous solution exhibits one quasi-reversible redox wave corresponding to Cu(II)/Cu(I) redox couple at a scan rate of 0.2 V s(-1). The shift in DeltaE(p), E(1/2) and I(pa)/I(pc) values ascertain the interaction of calf thymus DNA with copper(II) complex. There is decrease in viscosity of CTDNA which indicates that the complex 1 binds to CTDNA through a partial intercalative mode. The antibacterial and antifungal studies of the [C(7)H(6)N(2)S], [C(4)H(16)N(4)Cu]Cl(2,) [C(16)H(10)N(4)S(2)O(2)] and [C(20)H(22)N(8)S(2)Cu]Cl(2) were carried out against S. aureus, E. coli and A. niger. All the results reveal that the complex 1 is highly active against the bacterial strains and also inhibits fungal growth.

Anti-Bacterial Agents↗

PubMed2005

Electrochemical study on the behavior of Morin and its interaction with DNA.

Voltammetric behavior of Morin was studied in 0.1M HAc-NaAc+50mM KCl (pH 3.4) solution at glassy carbon electrode (GCE) using cyclic voltammetry (CV). Morin showed an irreversible anodic peak at 0.720 V in CV which was involving two electrons and two protons. Also, the interaction of Morin with double-stranded calf thymus DNA (ctDNA) was studied by CV at GCE with an irreversible electrochemical equation. As a result of reaction with ctDNA, the voltammetric peak of Morin was a position shift and the peak current decreased. The diffusion coefficients of both free and binding Morin (D(f)=1.1,086 x 10(-7)cm(2)s(-1) and D(b)=8.2,544 x 10(-9)cm(2)s(-1)), binding constant (K=1.7,765 x 10(7)cm(3)mol(-1)), and binding site size (s=0.8,510) of the Morin-DNA complex were obtained simultaneously by non-linear fit analysis. The results demonstrate that Morin can bind to ctDNA in 0.1M HAc-NaAc+50mM KCl (pH 3.4) solution and the ring B of Morin intercalates between the DNA base pairs.

Algorithms↗

PubMed2005

Determination of nucleic acids based on shifting the association equilibrium between tetracarboxy aluminum phthalocyanine and poly-lysine.

A new method based on near-infrared (near-IR) fluorescence recovery was presented for the determination of nucleic acids. This method employed a two-reagent system composed of anionic tetracarboxy aluminum phthalocyanine (AlC4Pc) and polycationic poly-lysine. The fluorescence of AlC4Pc, with the maximum excitation and emission wavelengths at 620 and 701 nm, respectively, was quenched by poly-lysine with a proper concentration, but recovered by adding nucleic acids. Under optimal conditions, the recovered fluorescence was in proportional to the concentration of nucleic acids. The linear ranges of the calibration curves were 5-200 ng mL(-1) for both calf thymus DNA (ctDNA) and fish sperm DNA (fsDNA) with the detection limit of 2.6 ng mL(-1) for ctDNA and 2.1 ng mL(-1) for fsDNA. The relative standard deviation (n = 6) was 1.9 and 1.3% for 50 ng mL(-1) ctDNA and fsDNA, respectively. The proposed method was applied to the determination of nucleic acids in synthetic samples with satisfactory results.

Animals↗

PubMed2006

LC/MS/MS method for the quantitation of trans-2-hexenal-derived exocyclic 1,N(2)-propanodeoxyguanosine in DNA.

trans-2-Hexenal is an alpha,beta-unsaturated aldehyde to which humans are exposed daily in small amounts. Hexenal has demonstrated mutagenicity and genotoxicity in vitro and reacts with deoxyguanosine to form diastereomeric hexenal-derived exocyclic 1,N(2)-propanodeoxyguanosine (Hex-PdG) adducts. A highly sensitive and specific method for the measurement of Hex-PdG in DNA has not previously been available. An LC/MS/MS assay for the quantitation of Hex-PdG, using [(13)C4(15)N2]Hex-PdG as an internal standard, was developed, to assess binding of hexenal to DNA. Samples were purified prior to analysis by centrifuge filtration and solid phase extraction and analyzed by LC/MS/MS in the selected reaction monitoring (SRM) mode (SRM m/z 366.2 --> 250.2 for Hex-PdG; SRM m/z 372.2 --> 256.2 for [(13)C4(15)N2]Hex-PdG). Recovery of standards was 89% or greater, and quantitation was unaffected by the addition of increasing concentrations of calf thymus DNA (ctDNA). The limit of quantitation, determined in samples of 200 microg of ctDNA spiked with analyte standard, was 0.015 fmol/microg DNA, which corresponds to approximately 5 Hex-PdG/10(9) unmodified nucleotides. Hex-PdG was detected in ctDNA treated with 0.021 microM, 0.21 microM, or 2.1 mM hexenal but not in untreated DNA. Furthermore, Hex-PdG was not detected in DNA exposed to reactive oxygen species-mediated deoxyribose attack and lipid peroxidation, which resulted in a significant increase in the malondialdehyde-derived pyrimido[1,2-a]purin-10(3H)one. Hex-PdG was not detected in DNA of untreated rat liver, but Hex-PdG in hexenal-treated calf thymus DNA was quantifiable when spiked into the rat liver DNA at 0.035 or 0.35 fmol/microg DNA. These data indicate that Hex-PdG is formed following hexenal treatment and that this method is suitable for in vitro or in vivo assessment of Hex-PdG formation.

Aldehydes↗

PubMed2026

Large-scale simulation of coverage and error rate tradeoffs for cancer detection in cell-free DNA whole-genome sequencing.

MOTIVATION: Cell-free DNA (cfDNA) whole-genome sequencing (WGS) is a promising approach for detecting cancer recurrence. It enables cancer detection by identifying all tumor-derived cfDNA (ctDNA) molecules carrying somatic single nucleotide variants (sSNVs). While ideally, a sequencing platform should be highly accurate for reliable ctDNA detection, in reality, all sequencing platforms introduce sequencing errors that generate false positives indistinguishable from true SNVs. Understanding how sequencing parameters influence ctDNA detection sensitivity at low tumor fractions (TFs) in cfDNA samples is essential for guiding sequencing strategies in clinical contexts. To model cfDNA sequencing for tumor detection, which contains asymmetric noise and multiple interacting parameters, analytical modeling is intractable, motivating large-scale parallelized simulation. RESULTS: We developed a simulation framework to generate in silico cfDNA data across 10 cancer types. In total, 480 million cfDNA samples were simulated from tumor WGS profiles. Overall, the lowest detectable TF differs substantially between cancer types under identical sequencing conditions due to variations in mutational load. For cancers with high mutational load, 3× coverage with low-error techniques reliably detects TFs below 0.1%. In contrast, cancers with low mutational load require at least six-fold higher coverage to achieve comparable detection thresholds. Increasing sequencing quality scores from Q30 to Q55 at 30× coverage further enhances sensitivity, enabling detection of TFs as low as 1 × 10-5. This study provides a comprehensive framework for optimizing sequencing parameters, offering valuable guidance for tailoring future technology development for specific cancer types and clinical applications. AVAILABILITY AND IMPLEMENTATION: The code is publicly available at https://github.com/UMCUGenetics/cfdetect/tree/main.

Whole Genome Sequencing↗

PubMed1989

Aspartate and asparagine tRNA genes in wheat mitochondrial DNA: a cautionary note on the isolation of tRNA genes from plants.

We have identified genes encoding a "native" tRNA(Asp) (trnD-GTC) and a "chloroplast-like" tRNA(Asn) (trnN-GTT) on opposite strands and 633 bp apart within a sequenced 1640 bp RsaI restriction fragment of wheat mtDNA. The trnD gene has been found previously at a different location in wheat mtDNA (P.B.M. Joyce et al. (1988) Piant Mol. Biol. 11, 833-843); the duplicate copies of this gene are identical within the coding and immediate flanking regions (9 bp downstream and at least 68 bp upstream), after which obvious sequence similarity abruptly disappears. The trnN gene is identical to its homolog in maize ctDNA; continuation of sequence similarity beyond the coding region suggests that this gene originated as promiscuous ctDNA that is now part of the wheat mitochondrial genome. In the course of this work, we have encountered some unexpected similarities between tRNA gene regions from wheat mitochondria and other sources. Detailed analysis of these similarities leads us to suggest that trnN genes reportedly from petunia nuclear DNA (N. Bawnik et al. (1983) Nucleic Acids Res. 11, 1117-1122) and lupine mtDNA (B. Karpińska and H. Augustyniak (1988) Nucleic Acids Res. 16, 6239) are, in fact, from petunia mtDNA and lupine ctDNA, respectively, whereas a putative wheat nuclear tRNA(Ser) (trnS-TGA) gene (Z. Szwekowska-Kulińska et al. (1989) Gene 77, 163-167) is actually from wheat mtDNA. In these instances, it seems probable that the DNA samples used for cloning contained trace amounts of DNA from another sub-cellular compartment, leading to the inadvertent selection of spurious clones.

Base Sequence↗

PubMed1998

A chloroplast DNA helicase II from pea that prefers fork-like replication structures

A DNA helicase, called chloroplast DNA (ctDNA) helicase II, was purified to apparent homogeneity from pea (Pisum sativum). The enzyme contained intrinsic, single-stranded, DNA-dependent ATPase activity and an apparent molecular mass of 78 kD on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The DNA helicase was markedly stimulated by DNA substrates with fork-like replication structures. A 5'-tailed fork was more active than the 3'-tailed fork, which itself was more active than substrates without a fork. The direction of unwinding was 3' to 5' along the bound strand, and it failed to unwind blunt-ended duplex DNA. DNA helicase activity required only ATP or dATP hydrolysis. The enzyme also required a divalent cation (Mg2+>Mn2+>Ca2+) for its unwinding activity and was inhibited at 200 mM KCl or NaCl. This enzyme could be involved in the replication of ctDNA. The DNA major groove-intercalating ligands nogalamycin and daunorubicin were inhibitory to unwinding (Ki approximately 0.85 &mgr;M and 2.2 &mgr;M, respectively) and ATPase (Ki approximately 1.3 &mgr;M and 3.0 &mgr;M, respectively) activities of pea ctDNA helicase II, whereas ellipticine, etoposide (VP-16), and camptothecin had no effect on the enzyme activity. These ligands may be useful in further studies of the mechanisms of chloroplast helicase activities.

Journal Article↗

PubMed1980

Sequence Homology between Chloroplast DNAs from Several Higher Plants.

An estimate has been made of the amount of sequence homology present in the chloroplast DNA (ctDNA) of several higher plants by the technique of DNA-DNA hybridization. Approximately 85% of tomato, 60% of spinach, 45% of kale, and 15% of barley ctDNA sequences were found to hybridize with tobacco ctDNA under conditions in which maximum hybridization in homologous reactions reached 85%. All heteroduplexes contained significant amounts of sequence mismatch as indicated by a 3 to 9 C decrease in melting temperature as compared to homoduplex.The data suggest that considerable sequence homology exists between the ctDNAs of these plants and that some sequences are held in common among all of the species tested.

Journal Article↗

PubMed2005

Heteroplasmy and paternally oriented shift of the organellar DNA composition in barley-wheat hybrids during backcrosses with wheat parents.

Mitochondrial (mt) and chloroplast (ct) genome inheritance was studied in barley-wheat hybrids, as were their progenies obtained from backcrosses with different common wheat cultivars, by monitoring the composition of 4 mtDNA (coxI, a 5'-flanking region of cob, nad3-orf156, and 5'-upstream region of 18S/5S) and 2 ctDNA (simple-sequence repeat locus downstream of trnS and a 3'-flanking region of rbcL) loci. In male sterile F1 and BC1 plants, maternal barley mtDNA fragments were mainly detected and very low levels of paternal wheat fragments were occasionally detected by PCR in coxI, a 5'-flanking region of cob and nad3-orf156, whereas a 5'-upstream region of 18S/5S showed clear heteroplasmy, containing both maternal and paternal copies, with maternal copies prevailing. Plants showing such heteroplasmic mtDNA composition remained either semisterile or became completely sterile in the later backcross generations. Only maternal ctDNA copies were detected in these plants. In 3 stable, self-fertile, and vigourous lines obtained in the advanced backcross generations and possessing recombinant wheat nuclear genome, however, only mt- and ctDNA copies of wheat parents were detected; thus, the original alloplasmic condition appeared to be lost. Our results suggest that transmission followed by selective replication of the paternal wheat organellar DNA leads to a paternally oriented shift of the organellar DNA composition in barley-wheat hybrids, which correlates with the restoration of fertility and plant vigour. These 2 processes seem to be related to nucleocytoplasmic compatibility and to be under the control of the nuclear genome composition.

Chimera↗

PubMed2026

Efficacy and Genomic Analysis of HER2-Mutant Metastatic Triple-Negative Breast Cancer Treated with Neratinib Alone or with Trastuzumab in the SUMMIT Basket Trial.

PURPOSE: Human epidermal growth factor receptor 2 (HER2) mutations occur in 1% to 3% of triple-negative breast cancers (TNBC), representing a novel target for biomarker-directed treatment. In the SUMMIT basket trial (NCT01953926), patients with HER2-mutant, metastatic TNBC received neratinib (240 mg/day) or neratinib + trastuzumab (N + T; neratinib 240 mg/day, intravenous trastuzumab 8 mg/kg initially and then 6 mg/kg every 3 weeks). We report final results from the neratinib and N + T TNBC cohorts. PATIENTS AND METHODS: Primary endpoint: investigator-assessed objective response rate at first postbaseline tumor assessment (ORRfirst); secondary endpoints included confirmed ORR by investigator, clinical benefit rate (CBR), and progression-free survival (PFS); exploratory endpoint included circulating tumor DNA (ctDNA) collected at baseline, during treatment, and at the end of treatment. RESULTS: Twenty-seven patients were enrolled between July 2014 and September 2021. Confirmed ORRs were 40% [95% confidence interval (CI), 12.2-73.8] for neratinib (n = 10) and 35.3% (95% CI, 14.2-61.7) for N + T (n = 17). CBRs were 40% (95% CI, 12.2-73.8) and 47.1% (95% CI, 23-72.2), respectively; median PFS times were 2.89 (95% CI, 0.95-5.52) and 6.24 months (95% CI, 2.10-8.18), respectively. HER2 mutation variant allele frequencies in ctDNA from patients with response or stable disease decreased upon treatment and increased upon progression. Serial ctDNA sequencing revealed emergence or increase in on-pathway (ERBB3) and off-pathway (KRAS and TP53) mutations. The most common treatment-emergent adverse events were diarrhea, nausea, and constipation. CONCLUSIONS: N + T in patients with HER2-mutant metastatic TNBC seemed to prolong responses versus neratinib alone, representing a novel approach for patients with biomarker-defined metastatic TNBC. Based on these and previously published data, neratinib-based combinations are endorsed by the National Comprehensive Cancer Network guidelines for patients with hormone receptor-positive or -negative metastatic breast cancer with activating HER2 mutations. See related commentary by Lloyd et al., p. 3715.

Adult↗

PubMed1975

The presence of covalently linked ribonucleotides in the closed circular deoxyribonucleic acid from higher plants.

Single-stranded scissions are induced in the covalently closed circular chloroplast (ct-) DNAs from peas, spinach, and lettuce plants by treatment with alkali or by incubation with a mixture of ribonucleases A and T1. These scissions are due to the presence of covalently linked ribonucleotides in these closed circular DNAs. By comparing the scission rates of these ctDNAs to the scission rate of RNA, it has been estimated that pea and spinach ctDNAs contain a maximum of 18 +/- 2 ribonucleotides/molecule, while lettuce ctDNA contains a maximum of 12 +/- 2 ribonucleotides/molecule. Further studies with pea ctDNA by electron microscopic methods have shown that pea ctDNA contains 19 alkali-labile sites at specific locations. A map of the relative positions of the alkali-labile sites has been constructed. These alkali-labile sites are presumably due to the insertion of individual ribonucleotides.

Alkaline Phosphatase↗

PubMed2006

[Selective determination for calf thymus DNA by a resonance light scattering technique with morin-Ce(IV) system].

The interaction of DNA and the binary complex formed between Ce(IV) and morin was studied. With the maximum scattering peak located at 320 nm, the enhanced RLS was proportional to the concentration of ctDNA in the range 0-25 microg x mL(-1) and the detection limit (3sigma) of 0.3 microg x mL(-1) was obtained. Under the optimized conditions, four synthetic samples were determined with recoveries in the range 93.7%-108.4%. The proposed method is particularly attractive for its high selectivity for ctDNA in the presence of hsDNA by using certain sensitive spectrofluorometer since the intensity of RLS for hsDNA is far weaker than that for ctDNA.

Animals↗

PubMed2026

Longitudinal genome-wide aneuploidy measurements in circulating cell-free DNA to predict lack of benefit from pembrolizumab in patients with metastatic urothelial cancer.

Accurate prediction of lack of benefit from pembrolizumab in patients with metastatic urothelial cancer (mUC) is an unmet need. We investigated the dynamics of circulating tumor DNA (ctDNA) load, estimated using the modified fast aneuploidy screening test-sequencing system (mFast-SeqS), as a potential biomarker for early on-treatment identification of treatment response. A total of 104 patients with mUC treated with pembrolizumab from two prospective biomarker discovery trials were included and mFast-SeqS was performed on paired blood samples collected at baseline and on-treatment. Patients with a high on-treatment aneuploidy score (≥ 5, n = 26) had a shorter median OS than patients with a low (< 5) score (n = 76) (3 vs 17 months: P-value< 0.001). Patients with an increased (n = 10), stable (n = 66), or decreased (n = 28) on-treatment score relative to their baseline score had a median PFS of 1.5, 4.0, and 8.3 months, respectively. Median OS was 3.0, 11.1, and 18.7 months, respectively. In patients with mUC treated with pembrolizumab, the on-treatment mFast-SeqS-based ctDNA level and its dynamics relative to baseline are independent prognostic markers that can be used to identify patients that are unlikely to benefit from pembrolizumab.

Humans↗

PubMedDate not supplied

Linear sweep voltammetric studies on the interaction of brilliant cresyl blue with nucleic acids and its analytical application.

In this paper, the interaction of brilliant cresyl blue (BCB) with nucleic acids was studied and further applied for the microdetermination of nucleic acids. In aqueous Britton-Robinson (B-R) buffer solution, BCB can be easily reduced on the hanging mercury drop electrode (HMDE) and had a sensitive voltammetric reduction peak at -0.09 V (vs. SCE). The reduction peak current of BCB could be greatly decreased by the addition of DNA. The results of voltammetric measurements had indicated that a binding reaction was occurred between BCB and DNA and a new supramolecular complex was formed, which resulted in the decrease of the diffusion coefficient of the reaction solution and the decrease of the reduction peak current correspondingly. The conditions of interaction and the electrochemical detection were carefully investigated. Under the selected conditions, the calibration curves for the detection of fish sperm (fs)DNA, calf thymus (ct)DNA and yeast (y)RNA were established. The linear range of this assay was 1.0-30.0 microg/mL for fsDNA, 1.0-45.0 microg/mL for ctDNA and 1.0-25.0 microg/mL for yRNA, respectively. The detection limits were 0.38 microg/mL fsDNA, 0.43 microg/mL ctDNA, 0.64 microg/mL yRNA. The interaction parameters such as the equilibrium constant and the binding number were calculated by electrochemical method. The results showed that the 2:3 type of complex was formed in the fsDNA-BCB complex with the binding constant as 2.51 x 10(7). The proposed method was further applied to the synthetic samples determination with satisfactory results.

Animals↗

PubMedDate not supplied

Determination of nucleic acids based on the quenching effect on resonance light scattering of the Y(III)-1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexane-dione system.

Nucleic acids can quench resonance light scattering (RLS) intensity of the Y(III)-1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexane-dione(BPMPHD) complex in the pH range 5.0-5.8. Under optimal conditions, there are linear relationships between the quenching of RLS and the concentration of nucleic acids in the range 6.3 x 10(-8)-2.1 x 10(-5) g/mL for fish sperm DNA (fsDNA), 1.2 x 10(-8)-5.0 x 10(-5) g/mL for calf thymus DNA (ctDNA) and 6.0 x 10(-8)-2.0 x 10(-5) g/mL for yeast RNA (yRNA). The detection limits (3 s) of fsDNA, ctDNA and yRNA are 0.7 ng/mL, 3.8 ng/mL and 4.2 ng/mL, respectively.

Aldehydes↗