Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: DNA adducts

Sortuj według:

Ogranicz wyniki do:

Wykorzystanie spektrometrii mas do analizy modyfikacji nukleotydów i adduktów DNA

Hanus J., Jelonek K., Pietrowska M.

Wiadomości Chemiczne

2011

[Z] 65, 3-4

191-205

Chemically modified nucleotides, which are not normally present in genetic material, are called DN A adducts. This type of DN A modifications (damage) is directly related to processes of mutagenesis and carcinogenesis. Elevated levels of DN A adducts present in genetic material reflect exposure of humans to carcinogenic factors and are markers of increased risk of cancer [1]. For this reason different methods useful for quantitative and qualitative analyses of DN A adducts are used in the field of cancer prevention and research (Tab. 1). Enzymatically-catalyzed methylation of cytosine, observed mostly in so called CpG islands, is a frequent endogenous modification of genetic material. Such a DN A methylation is a key factor involved in regulation of gene expression, and methylation status of oncogenes and tumor supressor genes is an important biomarker of carcinogenesis. As such, analytical methods for assessment of DN A methylation are of great importance for molecular diagnostics of cancer. During the last decade significant progress has been made in methods available for quantitative, qualitative and structural analyses of biological molecules. Among intensively developed tools for bioanalyses are methods of mass spectrometry. Spectrometers that are based on two methods of ionization, namely electrospray ionization (ESI ) [30] and matrix-assisted laser desorption-ionization (MALDI ) [48], are particularly suitable for analyses of biological macromolecules: proteins and nucleic acids. Currently available mass spectrometers, together with microscale methods for sample preparation and separation, significantly increased sensitivity and accessible mass range of analyses. New generation of “user-friendly” instruments is developed to bring the techniques directly into the workplaces of biological and clinical investigators. This review demonstrates representative examples of mass spectrometry techniques used for qualitative analyses of nucleotide modifications and adducts present in genetic material of humans. In this field several methods base on spectrometers with electrospray ionization. Generated ions are separated according to their mass-to-charge ratio in an analyzer by electric fields; among different ion analyzers frequently used in this methods are single or triple quadrupole and ion traps (Fig. 1). Among other methods available for assessment of DN A adducts is so called Accelerator Mass Spectrometry (Fig. 2) [41]. The most frequently applied method for the assessment of DN A methylation is based on methylation-specific PCR reaction. Products of such PCR reactions are analyzed using MALDI mass spectrometry [54] (Fig. 3). In summary, new powerful methods of mass spectrometry that made available qualitative analyses of damage and modifications of human genetic material found their important place in modern biological and medical laboratories.

Identification of Adducts Formed in the Reaction of the Bacterial Mutagen 3-Chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone with Cytidine

Pluskota-Karwatka D., Munter T., Le Curieux F., Sjöholm R., Koroniak H., Kronberg L.

Polish Journal of Chemistry

2007

Vol. 81, nr 5-6

1145-1157

3-Chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF), a strong bacterial mutagen reacts with cytidine in buffered aqueous solutions. The reaction products were separated by preparative HPLC C18 column chromatography and were structurally characterized by UV absorbance, 1H NMR and 13C NMR spectroscopy, and mass spectrometry. The main products were identified as 7-(-D-ribofuranosyl)-4-carboxy-6- oxo-6,7-dihydro-4H-pyrimido[1,6-alfa]pyrimidine-3-carbaldehyde (cM1FA-Cyd), and 7-(beta-D-ribofuranosyl)-6-oxo-6,7-dihydro-4H-pyrimido[1,6-alfa]pyrimidine-3-carbaldehyde (M1FA-Cyd). The highest yields of cM1FA-Cyd andM1FA-Cyd, being 12 and 1mol%respectively, were obtained in the reaction performed at pH 4.6 and 37 graduateC for 7 days. M1FA-Cyd and cM1FA-Cyd are structurally related to pfA-dR, the adduct previously identified in the reaction of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) or 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) with 2'-deoxyadenosine.

The Application of Qualitative Analysis of DNA Bulky Adducts in the Diagnoosis of Brain Tumours

Barciszewska A., Gawrońska I., Żukiel R., Nowak S., Barciszewska M. Z.

Polish Journal of Chemistry

2003

Vol. 77 / nr 11

1607-1614

Damage to DNA(base modification) is generally considered to be causative and directly related to tumour formation. Interaction of chemical carcinogens with DNA either directly or after metabolic activation, typically involves covalent binding of an electrophilic compound with a nucleophilic site in DNA. Guanine is by far the most prevalent target although adducts have been reported for all bases. We analysed the occurrence of bulky hydrophobic derivatives of DNA (adducts) in human brain tumour tissues. DNA was isolated, enzymatically digested to nucleotides and labeled with [_-32P]ATP and T4 polynucleotide kinase. Radioactive nucleotides were separated on anion-exchange polyethyleneimine cellulose (PEI) thin layer chromatography (TLC).We found that all brain tumours have similar DNA adducts pattern, although there are some significant differences for a particular disease. It turned out that DNA of a glioblastoma multiforme contains a rich array of modified bases in contrast to meningeoma tissues DNA, which shows only a few nucleotides. Location of spots on TLC of DNA adducts resemble a triangle, which is specific for brain tumours. This method of analysis may be very useful in classification and clinical diagnosis of brain tumours.