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1.
Photodiagnosis Photodyn Ther ; 46: 104060, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38521149

ABSTRACT

BACKGROUND: Cervical cancer (CC) occupies a leading position in incidence among young women of reproductive age. In this connection, it is urgent to search for the most effective approaches to the diagnosis and treatment of this pathology. The purpose of the study was to evaluate the effectiveness of the PDT method using Cе6 with the control of the photobleaching using video and spectral fluorescence diagnostic methods, to develop the method of fluorescence-assisted systemic photodynamic therapy mediated with chlorin e6 for treatment CIN 3 and CIS. MATERIALS AND METHODS: A randomized comparative clinical study was conducted involving 94 women aged 18 to 49 years with histologically verified severe intraepithelial squamous cell lesions of the cervix or preinvasive cervical cancer. The patients were included in 2 groups: in the first group conization of the cervix was performed with curettage of the remaining part of the cervical canal; patients in the second group underwent the chlorin e6-mediated fluorescence-assisted systemic photodynamic therapy. RESULTS: The absolute majority of patients in the main group after the first course of chlorin e6-mediated fluorescence-assisted systemic photodynamic therapy showed normalization of cytological parameters and colposcopic picture, while women from the comparison group showed signs of cervical lesions statistically significantly more often. These changes corresponded to the dynamics of the proliferation markers expression in the cells of intraepithelial squamous cell lesions. Also, patients of the second group who were planning a pregnancy had better reproductive outcomes after treatment compared to those of the first group. CONCLUSION: In general, higher clinical efficacy and safety of the use of the chlorin e6-mediated fluorescence-assisted systemic photodynamic therapy in the treatment of intraepithelial squamous cell lesions and preinvasive cervical cancer have been established compared to the use of standard treatment methods.


Subject(s)
Chlorophyllides , Conization , Photochemotherapy , Photosensitizing Agents , Porphyrins , Uterine Cervical Neoplasms , Humans , Female , Photochemotherapy/methods , Porphyrins/therapeutic use , Uterine Cervical Neoplasms/drug therapy , Photosensitizing Agents/therapeutic use , Adult , Conization/methods , Middle Aged , Adolescent , Young Adult , Uterine Cervical Dysplasia/drug therapy
2.
Materials (Basel) ; 16(3)2023 Jan 27.
Article in English | MEDLINE | ID: mdl-36770119

ABSTRACT

Amorphous carbon (AC) is present in the bulk and on the surface of nanostructured carbon materials (NCMs) and exerts a significant effect on the physical, chemical and mechanical properties of NCMs. Thus, the determination of AC in NCMs is extremely important for controlling the properties of a wide range of materials. In this work, a comparative study of the effect of heat treatment on the structure and content of amorphous carbon in deposited AC film, nanodiamonds, carbon black and multiwalled carbon nanotube samples was carried out by TEM, XPS, XRD and Raman spectroscopy. It has been established that the use of the 7-peak model for fitting the Raman spectra makes it possible not only to isolate the contribution of the modes of amorphous carbon but also to improve the accuracy of fitting the fundamental G and D2 (D) modes and obtain a satisfactory convergence between XPS and Raman spectroscopy. The use of this model for fitting the Raman spectra of deposited AC film, ND, CB and MWCNT films demonstrated its validity and effectiveness for investigating the amorphous carbon in various carbon systems and its applicability in comparative studies of other NCMs.

4.
Biochemistry (Mosc) ; 85(4): 480-489, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32569555

ABSTRACT

Damaged DNA bases are removed by the base excision repair (BER) mechanism. This enzymatic process begins with the action of one of DNA glycosylases, which recognize damaged DNA bases and remove them by hydrolyzing N-glycosidic bonds with the formation of apurinic/apyrimidinic (AP) sites. Apurinic/apyrimidinic endonuclease 1 (APE1) hydrolyzes the phosphodiester bond on the 5'-side of the AP site with generation of the single-strand DNA break. A decrease in the functional activity of BER enzymes is associated with the increased risk of cardiovascular, neurodegenerative, and oncological diseases. In this work, we developed a fluorescence method for measuring the activity of key human DNA glycosylases and AP endonuclease in cell extracts. The efficacy of fluorescent DNA probes was tested using purified enzymes; the most efficient probes were tested in the enzymatic activity assays in the extracts of A549, MCF7, HeLa, WT-7, HEK293T, and HKC8 cells. The activity of enzymes responsible for the repair of AP sites and removal of uracil and 5,6-dihydrouracil residues was higher in cancer cell lines as compared to the normal HKC8 human kidney cell line.


Subject(s)
DNA Damage , DNA Glycosylases/metabolism , DNA Probes/chemistry , DNA Repair Enzymes/metabolism , DNA Repair , Enzyme Assays/methods , Fluorescent Dyes/chemistry , Cell Extracts , Cells, Cultured , DNA Repair Enzymes/genetics , Humans
5.
Urologiia ; (1): 121-126, 2020 Mar.
Article in Russian | MEDLINE | ID: mdl-32191014

ABSTRACT

The article is devoted to the interaction of a gynecologist and a urologist in a gynecological hospital, based on the experience of the gynecological department at the Clinic of obstetrics and gynecology of the Clinical Center of Sechenov University. The most common clinical scenarios were identified when the participation of a urologist in evaluation and treatment is urgently needed, including large pelvis mass, endometriosis with an involvement of pelvic organs, genital prolapse, small pelvis adhesions as a result of previous surgical procedures and postoperative urinary disorders. A close interaction between two specialties, which are dedicated to pelvic organs disorders, namely gynecology and urology, is extremely popular in modern clinical practice and allows to significantly reduce the number of intra- and postoperative complications, carry out a comprehensive examination and determine individual treatment tactics in a gynecological hospital, which increases quality of medical care.


Subject(s)
Endometriosis , Gynecology , Urology , Uterine Prolapse , Female , Humans , Pregnancy , Urologists
6.
Khirurgiia (Mosk) ; (5): 38-41, 2019.
Article in Russian | MEDLINE | ID: mdl-31169817

ABSTRACT

AIM: To develop treatment strategy in pregnant women with liver echinococcosis. MATERIAL AND METHODS: There were 21 women with confirmed diagnosis of liver echinococcosis who were divided into 2 groups. Group I consisted of 17 patients with cysts Charbi grade I-III. They underwent percutaneous puncture and antiparasitic management of the cyst under intravenous sedation. Group II included 4 patients with cysts grade IV-V and those with multiple cysts. They underwent conventional surgery. RESULTS: In one patient, fetal death occurred in 20 hours after surgery and it was not associated with the procedure. There were no complications in other patients. Uneventful childbirth was noted in all of them. CONCLUSION: Percutaneous puncture in the second trimester of pregnancy is effective and safe procedure for prevention of complications of echinococcosis in late pregnancy and childbirth. Conventional surgery is alternative if percutaneous intervention is not advisable.


Subject(s)
Drainage/methods , Echinococcosis, Hepatic/surgery , Pregnancy Complications, Infectious/surgery , Antiparasitic Agents/therapeutic use , Echinococcosis, Hepatic/drug therapy , Female , Humans , Pregnancy , Pregnancy Complications, Infectious/drug therapy , Pregnancy Trimester, Second
7.
Dokl Biochem Biophys ; 482(1): 233-237, 2018 Sep.
Article in English | MEDLINE | ID: mdl-30397881

ABSTRACT

Poly(ADP-ribosyl)ation, which is catalyzed by PARP family proteins, is one of the main reactions in the cell response to genomic DNA damage. Massive impact of DNA-damaging agents (such as oxidative stress and ionizing radiation) causes numerous breaks in DNA. In this case, the development of a fast cell response, which allows the genomic DNA integrity to be retained, may be more important than the repair by more accurate but long-term restoration of the DNA structure. This is the first study to show the possibility of eliminating DNA breaks through their PARP3-dependent mono(ADP-ribosyl)ation followed by ligation and repair of the formed ribo-AP sites by the base excision repair (BER) enzyme complex. Taken together, the results of the studies on ADP-ribosylation of DNA and the data obtained in this study suggest that PARP3 may be a component of the DNA break repair system involving the BER enzyme complex.


Subject(s)
Cell Cycle Proteins/pharmacology , DNA Breaks , DNA Repair/drug effects , Poly(ADP-ribose) Polymerases/pharmacology , Animals , Humans , Signal Transduction/drug effects
8.
RSC Adv ; 8(63): 35903-35916, 2018 Oct 22.
Article in English | MEDLINE | ID: mdl-35558492

ABSTRACT

The so-called M1 phase (the common formula (TeO) x (Mo, V, Nb)5O14) is a very promising catalyst for ethane oxidative dehydrogenation (ODE). It shows 90% selectivity to ethylene at 78% ethane conversion (400 °C, contact time - 5.5 s). The active crystal structure is formed under certain synthetic conditions in VMoNbTe mixed oxides. This paper is devoted to the analysis of how the local and average structure of the M1 phase is developed during the synthesis and what happens at particular synthetic steps. The analysis of the local structure was performed using the EXAFS and pair distribution function (PDF) methods. The EXAFS analysis of the initial VMoTe water solution and VMoNbTe slurry showed that Anderson-type heteropoly anions are formed in the solution and are preserved after fast spray-drying of the slurry. Nb cations do not enter the structure of the polyanions, but form an extended hydrated oxide matrix, where distorted NbO6 and NbO7 polyhedrons are connected to each other. The hydrated oxide matrix with captured polyanions provides the compositional homogeneity of the precursor. The distances in the second coordination shell are redistributed after thermal treatment at 310 °C. After being heated at T > 350°, the local structure of the M1 phase is organized and pentagonal domains are formed. These domains consist of a NbO7 pentagonal bipyramid and five MeO6 adjacent octahedra (Me = Mo, V). In the first stages, the building blocks are stacked along the [001] direction. The crystallization process results in the connection of the pentagonal domains to the extended polygonal grid. The formation of the regular grid with TeO x containing channels is accompanied by the increase in ethane conversion and ethylene selectivity of the catalysts.

9.
Sci Rep ; 7: 41811, 2017 02 06.
Article in English | MEDLINE | ID: mdl-28165484

ABSTRACT

The complex of two membrane proteins, sensory rhodopsin II (NpSRII) with its cognate transducer (NpHtrII), mediates negative phototaxis in halobacteria N. pharaonis. Upon light activation NpSRII triggers a signal transduction chain homologous to the two-component system in eubacterial chemotaxis. Here we report on crystal structures of the ground and active M-state of the complex in the space group I212121. We demonstrate that the relative orientation of symmetrical parts of the dimer is parallel ("U"-shaped) contrary to the gusset-like ("V"-shaped) form of the previously reported structures of the NpSRII/NpHtrII complex in the space group P21212, although the structures of the monomers taken individually are nearly the same. Computer modeling of the HAMP domain in the obtained "V"- and "U"-shaped structures revealed that only the "U"-shaped conformation allows for tight interactions of the receptor with the HAMP domain. This is in line with existing data and supports biological relevance of the "U" shape in the ground state. We suggest that the "V"-shaped structure may correspond to the active state of the complex and transition from the "U" to the "V"-shape of the receptor-transducer complex can be involved in signal transduction from the receptor to the signaling domain of NpHtrII.


Subject(s)
Archaeal Proteins/metabolism , Sensory Rhodopsins/metabolism , Signal Transduction , Archaeal Proteins/chemistry , Binding Sites , Halobacteriaceae/metabolism , Magnetic Resonance Spectroscopy , Models, Molecular , Protein Binding , Protein Conformation , Protein Interaction Domains and Motifs , Protein Multimerization , Sensory Rhodopsins/chemistry , Static Electricity , Structure-Activity Relationship
10.
Phys Chem Chem Phys ; 18(5): 3444-53, 2016 Feb 07.
Article in English | MEDLINE | ID: mdl-26743674

ABSTRACT

A vinylogous series of highly dipolar merocyanines were designed to study their solvatochromism in a wide range of solvents including low-polarity alkanes. It has been revealed that the lower vinylogues indeed have negative solvatochromism in the full range of solvent polarities starting from n-hexane, while the hexamethinemerocyanine exhibits reversed solvatochromism. With the extreme ranges of solvatochromism, the studied dyes possess 5-7 times weaker solvatofluorochromism, which can be rationalized via their decreased dipolarity in the fluorescent state. They also demonstrate an inverse dependence of their fluorescence quantum yield on solvent polarity and have near-record Stokes shifts in high-polarity media. The experimental data are supplemented by the results of DFT quantum chemical analysis of dye electronic structures in both the ground and excited states with PCM solvent field simulation.

11.
Vestn Ross Akad Med Nauk ; 71(6): 413-9, 2016.
Article in Russian | MEDLINE | ID: mdl-29298001

ABSTRACT

Objectives: According to different authors, the percentage of genital prolapse among gynaecological diseases that require surgical correction reaches 28−38,9%. Pelvic muscle wasting is a special kind of pelvic prolapse, often leading to cervical elongation and hypertrophy. Contemporary methods of treatment for this condition have the high rate of relapse­ 8,9−22%, thus urging to improve the existing techniques. Purpose: This research was to estimate the effectiveness of novel modification of Manchester operation in comparison with classic Manchester operation in the management of pelvic prolapse with cervical elongation. Methods: We enrolled 83 patients with pelvic prolapse and cervical elongation and divided them into two groups. In GroupI (n=47) we used the novel surgical method, supplementing original Manchester procedure with cervical stump fixation and other improvements. In GroupII we used original Manchester procedure. We compared laboratory measures as well as surgery duration, blood loss, incidence of complications, and duration of post-operational hospital stay. Patients were followed-up for 2years to estimate long-term effectiveness of surgical intervention. Statistical analysis was performed in SPSS 17.0. Results: Surgery duration in GroupII was significantly longer (47,8±26,2 vs 57,5±35,1 minutes, p<0.05). There were no significant differences in lab tests, post-operational hospital stay (5,2±0,9 vs 7,3±1,2) and incidence of post-operational complications (3 vs 4 cases). Over the 2 years of follow-up we registered 1 case of relapse in Group I and 3 cases of relapse in Group II, thus estimating the effectiveness of surgery as 97,9 vs 91,7%, a non-significant difference. We noticed that all relapsed women had signs of systemic dysplasia of connective tissue. Conclusion: Suggested modification of Manchester operation improves duration of surgical intervention itself, while providing a comparable level of effectiveness.


Subject(s)
Gynecologic Surgical Procedures , Postoperative Complications , Uterine Prolapse , Aged , Female , Gynecologic Surgical Procedures/adverse effects , Gynecologic Surgical Procedures/methods , Humans , Long Term Adverse Effects/diagnosis , Long Term Adverse Effects/etiology , Middle Aged , Operative Time , Postoperative Complications/diagnosis , Postoperative Complications/etiology , Recurrence , Treatment Outcome , Uterine Prolapse/diagnosis , Uterine Prolapse/surgery
12.
Bull Exp Biol Med ; 158(5): 607-10, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25778643

ABSTRACT

Behavioral, hormonal, and neurotransmitter reactions to foot shock were studied in adult rats treated with IL-1ß during week 3 of life. After stress, these animals differed from controls treated with saline by high levels of dopamine, serotonin, and 5-hydroxy-indolacetic acid in the hypothalamus. In contrast to controls, they developed a significant stress-induced increase of blood corticosterone level and exhibited lesser motor and exploratory activities in the open field test.


Subject(s)
Interleukin-1beta/blood , Neurotransmitter Agents/blood , Stress, Psychological/blood , Animals , Behavior, Animal/drug effects , Corticosterone/blood , Dopamine/blood , Hypothalamus/metabolism , Male , Rats , Rats, Wistar , Serotonin/blood , Stress, Psychological/physiopathology
13.
Lupus ; 24(7): 760-3, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25631855

ABSTRACT

We describe the case of a 67-year-old Asian female patient suffering from severe systemic lupus erythematosus (SLE), including biopsy-proven glomerulonephritis, since the age of 40 who was admitted for tetraparesis. Neurological examination confirmed proximal muscular weakness, hypoesthesia and diminished tendon reflexes. The patient suffered from extremely severe Jaccoud's arthropathy. Magnetic resonance imaging (MRI) demonstrated severe narrowing of the upper spinal canal due to a soft tissue mass surrounding the odontoid process, assumed to be a synovial pannus, causing myelopathy. The patient was treated with three intravenous pulses of methylprednisolone with prompt and full clinical recovery. Follow-up MRI confirmed considerable regression of the pannus. Inflammatory transverse myelopathy is the most common explanation for para/tetraparesis in SLE. However, in this case, the symptoms were caused by atlantoaxial synovitis, which is more typical for rheumatoid arthritis.


Subject(s)
Lupus Erythematosus, Systemic/complications , Quadriplegia/etiology , Aged , Atlanto-Axial Joint/pathology , Female , Glomerulonephritis/drug therapy , Glomerulonephritis/etiology , Glomerulonephritis/pathology , Glucocorticoids/administration & dosage , Humans , Lupus Erythematosus, Systemic/pathology , Methylprednisolone/administration & dosage , Quadriplegia/drug therapy , Quadriplegia/pathology
14.
Ross Fiziol Zh Im I M Sechenova ; 100(9): 1025-37, 2014 Sep.
Article in Russian | MEDLINE | ID: mdl-25697011

ABSTRACT

According to the Neurodevelopmental hypothesis, the long-lasting cognitive deficit in schizophrenia and other types of neuropathology may occur by injurious factors, such as hypoxia, traumas, infections that take place during pre- and postnatal development, at least at early stages. These pathological conditions are often associated with the high production of pro-inflammatory cytokine interleukin-1B (IL-1B) by the cells of immune and nervous systems. We investigated the expression of genes involved in the neuroplastic regulation (Fgf2 and Timp2) in medial prefrontal cortex and dorsal and ventral regions of hippocampus of adult rats that were treated with IL-1beta between P15 and P21. The learning impairment in IL-1beta-treated rats is accompanied by lower FGF-2 mRNA levels in medial prefrontal cortex and ventral (not dorsal) hippocampus, but TIMP-1 was not affected. No differences in TIMP-1 and FGF-2 mRNA expressions were observed in untrained IL-1beta-treated when compared to control rats.


Subject(s)
Fibroblast Growth Factor 2/biosynthesis , Gene Expression Regulation/drug effects , Hippocampus/growth & development , Interleukin-1beta/pharmacology , Prefrontal Cortex/growth & development , RNA, Messenger/biosynthesis , Tissue Inhibitor of Metalloproteinase-1/biosynthesis , Animals , Hippocampus/pathology , Hypoxia, Brain/metabolism , Hypoxia, Brain/pathology , Interleukin-1beta/metabolism , Male , Prefrontal Cortex/pathology , Rats , Rats, Wistar
15.
Prikl Biokhim Mikrobiol ; 50(6): 587-92, 2014.
Article in Russian | MEDLINE | ID: mdl-25726667

ABSTRACT

The effect of exogenous calcium (Ca2+) and rhizobial infections (Rhizobium leguminosarum bv viceae) on the dynamics of the level of nitric oxide (NO) was studied in cross cuts of roots of two-day-old etiolated pea seedlings (Pisum sativum L.) using a DAF-2DA fluorescent probe. Fluctuations of the NO level, indicating the presence of a rhythm in the generation of NO in roots, were observed during the incubation of seedlings in water, a CaCl2 solution, and with rhizobial infections. Exogenous factors (Ca2+ and two rhizobial stamms) change the time dynamics of the NO level in comparison with the control (water).


Subject(s)
Nitric Oxide/biosynthesis , Pisum sativum/metabolism , Plant Roots/metabolism , Rhizobium leguminosarum/physiology , Seedlings/metabolism , Calcium Chloride/pharmacology , Circadian Rhythm/physiology , Etiolation , Fluorescein , Fluorescent Dyes , Light , Pisum sativum/drug effects , Pisum sativum/microbiology , Plant Roots/drug effects , Plant Roots/microbiology , Seedlings/drug effects , Seedlings/microbiology , Signal Transduction , Spectrometry, Fluorescence
16.
Prikl Biokhim Mikrobiol ; 49(3): 236-41, 2013.
Article in Russian | MEDLINE | ID: mdl-23882941

ABSTRACT

Changes in the functional activity of the NADPH oxidase in the microsomal fraction of roots of etiolated pea seedlings, caused by rhizobial inoculation and calcium ions (Ca2+), are shown. The enzyme activity in a medium with an exogenous source of Ca2+ (CaCl2, 100 microM) fluctuated, increasing 5 to 20 min and decreasing 10 and 30 min after addition. A calcium chelator (ethylene glycol tetraacetic acid (EDTA), 100 microM) potentiated the decrease in the enzyme activity in the presence of exogenous calcium. Rhizobial inoculation caused a 3.9-fold increase in the enzyme activity 5 min after inoculation compared to the control (without inoculation). The Ca(2+)-channel activator (amiodarone, 300 microM) and the Ca(2+)-channel blocker (lanthanum chloride, 400 microM) reduced the NADPH oxidase activity after rhizobial inoculation compared to the control level (without inoculation). It is concluded that Ca2+ and reactive oxygen species are involved in the regulation of the membrane NADPH oxidase activity in roots of pea seedlings.


Subject(s)
NADPH Oxidases/metabolism , Pisum sativum/enzymology , Plant Roots/enzymology , Calcium/pharmacology , Ions/pharmacology , Oxidation-Reduction , Pisum sativum/growth & development , Reactive Oxygen Species/metabolism , Rhizobium leguminosarum/growth & development , Rhizobium leguminosarum/metabolism , Seedlings/enzymology , Seedlings/growth & development
17.
J Photochem Photobiol B ; 123: 55-8, 2013 Jun 05.
Article in English | MEDLINE | ID: mdl-23619282

ABSTRACT

The complex of sensory rhodopsin II (NpSRII) with its cognate transducer (NpHtrII) mediates negative phototaxis in halobacteria Natronomonas pharaonis. Upon light activation NpSRII triggers, by means of NpHtrII, a signal transduction chain homologous to the two component system in eubacterial chemotaxis. Here we report on the crystal structure of the ground state of the mutant NpSRII-D75N/NpHtrII complex in the space group I212121. Mutations of this aspartic acid in light-driven proton pumps dramatically modify or/and inhibit protein functions. However, in vivo studies show that the similar D75N mutation retains functionality of the NpSRII/NpHtrII complex. The structure provides the molecular basis for the explanation of the unexpected observation that the wild and the mutant complexes display identical physiological response on light excitation.


Subject(s)
Archaeal Proteins/chemistry , Carotenoids/chemistry , Halorhodopsins/chemistry , Intracellular Signaling Peptides and Proteins/chemistry , Rhodopsins, Microbial/chemistry , Sensory Rhodopsins/chemistry , Archaeal Proteins/genetics , Archaeal Proteins/physiology , Archaeal Proteins/radiation effects , Carotenoids/genetics , Carotenoids/radiation effects , Crystallography, X-Ray , Halobacteriaceae/chemistry , Hydrogen Bonding , Intracellular Signaling Peptides and Proteins/genetics , Light , Models, Molecular , Multiprotein Complexes/chemistry , Multiprotein Complexes/radiation effects , Rhodopsins, Microbial/genetics , Signal Transduction
18.
Izv Akad Nauk Ser Biol ; (6): 689-95, 2013.
Article in Russian | MEDLINE | ID: mdl-25518555

ABSTRACT

Data regarding the interrelation of nitric oxide (NO) content in roots of 3-day-old etiolated pea seedlings and their growth under different concentrations of N-containing compounds were obtained. The concentration of exogenous compounds (sodium nitroprusside SNP, KNO3, NaNO2, L-arginine) rendering an inhibiting effect on the growth of roots were established, and the NO content in roots was determined at these concentration. It was shown that the inhibition of growth and highest NO content in the roots was determined with SNP (4 mM) and NaNO2 (2 mM) during 24 h exposition of seedlings. This dependence was not established in combinations with KNO3 (20 mM) and L-arginine (4 mM). We established that a NO scavenger, hemoglobin (4 µM), fully or partially removed the toxic effect of SNP, nitrate, and nitrite on growth. The effect of NO on the growth and the participation of N-containing compounds in generation of NO in roots of pea seedlings is discussed.


Subject(s)
Nitric Oxide/metabolism , Pisum sativum/metabolism , Seedlings/metabolism , Arginine/pharmacology , Nitrates/pharmacology , Pisum sativum/drug effects , Pisum sativum/growth & development , Plant Growth Regulators/pharmacology , Plant Roots/drug effects , Plant Roots/growth & development , Plant Roots/metabolism , Seedlings/drug effects , Seedlings/growth & development
19.
Biochemistry (Mosc) ; 77(10): 1162-71, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23157296

ABSTRACT

The apurinic/apyrimidinic endonuclease from Saccharomyces cerevisiae Apn1 is one of the key enzymes involved in base excision repair of DNA lesions. A major function of the enzyme is to cleave the upstream phosphodiester bond of an apurinic/apyrimidinic site (AP-site), leading to the formation of a single-strand break with 3'-hydroxyl (OH) and 5'-deoxyribose phosphate (dRP) termini. In this study, the pre-steady-state kinetics and conformational dynamics of DNA substrates during their interaction with Apn1 were investigated. A stopped-flow method with detection of the fluorescence intensity of 2-aminopurine and pyrrolocytosine located adjacent or opposite to the damage was used. It was found that upon interaction with Apn1, both DNA strands undergo a number of rapid changes. The location of fluorescent analogs of heterocyclic bases in DNA does not influence the catalytic step of the reaction. Comparison of data obtained for yeast Apn1 and reported data (Kanazhevskaya, L. Yu., Koval, V. V., Vorobjev, Yu. N., and Fedorova, O. S. (2012) Biochemistry, 51, 1306-1321) for human Ape1 revealed some differences in their interaction with DNA substrates.


Subject(s)
DNA Repair Enzymes/metabolism , DNA/metabolism , Endodeoxyribonucleases/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/enzymology , Base Sequence , Binding Sites , DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism , Humans , Kinetics , Molecular Sequence Data , Substrate Specificity
20.
Biochemistry (Mosc) ; 77(3): 270-9, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22803944

ABSTRACT

Trinucleotide repeat expansion provides a molecular basis for several devastating neurodegenerative diseases. In particular, expansion of a CAG run in the human HTT gene causes Huntington's disease. One of the main reasons for triplet repeat expansion in somatic cells is base excision repair (BER), involving damaged base excision and repair DNA synthesis that may be accompanied by expansion of the repaired strand due to formation of noncanonical DNA structures. We have analyzed the kinetics of excision of a ubiquitously found oxidized purine base, 8-oxoguanine (oxoG), by DNA glycosylase OGG1 from the substrates containing a CAG run flanked by AT-rich sequences. The values of k(2) rate constant for the removal of oxoG from triplets in the middle of the run were higher than for oxoG at the flanks of the run. The value of k(3) rate constant dropped starting from the third CAG-triplet in the run and remained stable until the 3'-terminal triplet, where it decreased even more. In nuclear extracts, the profile of oxoG removal rate along the run resembled the profile of k(2) constant, suggesting that the reaction rate in the extracts is limited by base excision. The fully reconstituted BER was efficient with all substrates unless oxoG was near the 3'-flank of the run, interfering with the initiation of the repair. DNA polymerase ß was able to perform a strand-displacement DNA synthesis, which may be important for CAG run expansion initiated by BER.


Subject(s)
DNA Damage/drug effects , DNA Repair/drug effects , Guanine/analogs & derivatives , Trinucleotide Repeats/drug effects , Cell Line , DNA Glycosylases/genetics , Guanine/toxicity , Humans
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