Thermodynamics of hydrolysis of oligosaccharides

Microcalorimetry has been used to determine enthalpy changes for the hydrolysis of a series of oligosaccharides. High-pressure liquid chromatography was used to determine the extents of reaction and to check for any possible side reactions. The enzyme glucan 1,4-alpha-glucosidase was used to bring about the following hydrolysis reactions: (A) maltose(aq) + H2O(liq) = 2D-glucose(aq); (B) maltotriose(aq) + 2H2O(liq) = 3D-glucose(aq); (C) maltotetraose(aq) + 3H2O(liq) = 4D-glucose(aq); (D) maltopentaose(aq) + 4H2O(liq) = 5D-glucose(aq); (E) maltohexaose(aq) + 5H2O(liq) = 6D-glucose(aq); (F) maltoheptaose(aq) + 6H2O(liq) = 7D-glucose(aq); (G) amylose(aq) + nH2O(liq) = (n + 1) D-glucose(aq); and (H) panose(aq) + 2H2O(liq) = 3D-glucose(aq); (J) isomaltotriose(aq) + 2H2O(liq) = 3D-glucose(aq). The enzyme beta-fructofuranosidase was used for the reactions: (K) raffinose(aq) + H2O(liq) = alpha-D-melibiose(aq) + D-fructose(aq); and (L) stachyose(aq) + H2O(liq) = o-alpha-D-galactopyranosyl-(1----6)- alpha-o-D-galactopyranosyl-(1----6)-alpha-D-glucopyranose + D-fructose(aq). The results of the calorimetric measurements (298.15 K, 0.1 M sodium acetate buffer, pH 4.44-6.00) are: delta H0A = -4.55 +/- 0.10, delta H0B = -9.03 +/- 0.10, delta H0C = -13.79 +/- 0.15, delta H0D = -18.12 +/- 0.10, delta H0E = -22.40 +/- 0.15, delta H0F = -26.81 +/- 0.20, delta H0H = 1.46 +/- 0.40, delta H0J = 11.4 +/- 2.0, delta H0K = -15.25 +/- 0.20, and delta H0L = -14.93 +/- 0.20 kJ mol-1. The enthalpies of hydrolysis of two different samples of amylose were 1062 +/- 20 and 2719 +/- 100 kJ mol-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

The development of rating of perceived exertion-based tests of physical working capacity

The purpose of the present study was to use ratings of perceived exertion (RPE) from the Borg (6-20) and OMNI-Leg (0-10) scales to determine the Physical Working Capacity at the Borg and OMNI thresholds (PWC(BORG) and PWC(OMNI)). PWC(BORG) and PWC(OMNI) were compared with other fatigue thresholds determined from the measurement of heart rate (the Physical Working Capacity at the Heart Rate Threshold: PWC(HRT)), and oxygen consumption (the Physical Working Capacity at the Oxygen Consumption Threshold, PWC(VO2)), as well as the ventilatory threshold (VT). Fifteen men and women volunteers (mean age +/- SD = 22 +/- 1 years) performed an incremental test to exhaustion on an electronically braked ergometer for the determination of VO2 peak and VT. The subjects also performed 4 randomly ordered workbouts to exhaustion at different power outputs (ranging from 60 to 206W) for the determination of PWC(BORG), PWC(OMNI), PWC(HRT), and PWC(VO2). The results indicated that there were no significant mean differences among the fatigue thresholds: PWC(BORG) (mean +/- SD = 133 +/- 37W; 67 +/- 8% of VO2 peak), PWC(OMNI) (137 +/- 44W; 68 +/- 9% of VO2 peak), PWC(HRT) (135 +/- 36W; 68 +/- 8% of VO2 peak), PWC(VO2) (145 +/- 41W; 72 +/- 7% of VO2 peak) and VT (131 +/- 45W; 66 +/- 8% of VO2 peak). The results of this study indicated that the mathematical model used to estimate PWC(HRT) and PWC(VO2) can be applied to ratings of perceived exertion to determine PWC(BORG) and PWC(OMNI) during cycle ergometry. Salient features of the PWC(BORG) and PWC(OMNI) tests are that they are simple to administer and require the use of only an RPE scale, a stopwatch, and a cycle ergometer. Furthermore, the power outputs at the PWC(BORG) and PWC(OMNI) may be useful to estimate the VT noninvasively and without the need for expired gas analysis.     

Synthesis of the nucleoside moiety of liposidomycins: elucidation of the pharmacophore of this family of MraY inhibitors

Tunicamycins (TCMs) and liposidomycins (LPMs) are naturally occurring inhibitors of the bacterial translocase (MraY). Based on structure-activity relationship (SAR) studies, a molecular model has been proposed for their inhibitory mechanism. This study points out the importance of the nucleoside moiety of liposidomycins in the inhibition of MraY. A simplified molecule (I) based on the liposidomycin core structure has been synthesised and tested on MraY. The compound displayed a moderate inhibitory activity (IC50 = 50 microM). The validation of the molecular model was then performed by synthesising higher homologues of I, containing an additional stereocentre in the 5' position (XIV and XV). In agreement with the prediction, only the (S) isomer XV showed significant activity against MraY (IC50 = 5 microM).     

Synthesis of an octasaccharide fragment of high-mannose-type glycans of glycoproteins.

O-(alpha-D-Mannopyranosyl)-(1----2)-O-(alpha-D-mannopyranosyl)-(1----3)- O- [(alpha-D-mannopyranosyl)-(1----2)-O-(alpha-D-mannopyranosyl)-(1----6)]- O- (alpha-D-mannopyranosyl)-(1----6)-O-(beta-D-mannopyranosyl)-(1----4)-O-( 2- acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----4)-2-acetamido-2-deoxy- glucopyranose, an octasaccharide fragment of high-mannose type glycan of glycoproteins, was synthesized. Crucial glycosylation of trisaccharide intermediate, benzyl O-(2,4-di-O-benzyl-beta-D-mannopyranosyl)-(1----4)-O-(2-acetamido-3,6-di -O- benzyl-2-deoxy-beta-D-glucopyranosyl)-(1----4)-2-acetamido-3,6-di-O-benz yl-2- deoxy-beta-D-glucopyranoside, was successful only with a di-O-acetyltetradeca-O-benzyl-D-mannopentaosyl chloride. The use of the corresponding hexadeca-O-acetyl-D-mannopentaosyl bromide did not give the desired product.     

Analysis of reproductive parameters of urban and rural population of Chuvashia

Genetic and demographic characteristics for urban and rural population of the Chuvash Republic (Chuvashes and Russians) were calculated based on 1122 questionnaires. The sibship sizes for Chuvashes were 2.05 (urban) and 2.78 (rural). For Russians these indices were 1.75 (urban) and 2.00 (rural), respectively. Crow's index and its components were I(m) = 0.04; I(f) = 0.18; and I(tot) = 0.22 for urban, and I(m) = 0.07; I(f) = 0.27; and I(tot) = 0.36 for rural Chuvashes, respectively; and I(m) = 0.04; I(f) = 0.30; and I(tot) = 0.36 for urban, and I(m) = 0.03; I(f) = 0.29; and I(tot) = 0.33 for rural Russians, respectively.     

Investigation of the mechanism of nicotine-induced relaxation on the sheep sphincter of Oddi

Possible mechanisms for nicotine-induced relaxation were investigated in the isolated sheep's sphincter of Oddi. Sheep's sphincter of Oddi rings were mounted in tissue bath with modified Krebs-Henseleit solution and aerated with 95% oxygen and 5% carbon dioxide. Tension was measured with isometric force transducers, and muscle relaxation was expressed as percent decrease of precontraction induced by carbachol. Nicotine (1 x 10(-5) to 3 x 10(-3) mol/L) produced concentration-dependent relaxation on sphincter of Oddi precontracted by carbachol (10(-6) mol/L). Nicotine-induced relaxation was 72.8 +/- 4.2% of precontraction with carbachol (10(-6) mol/L) (mean pD2 value, 3.76 +/- 0.05 mol/L). Nicotine-induced relaxation was not affected by N(w)-nitro L-arginine methyl ester (L-NAME) (3 x 10(-5) mol/L), methylene blue (10(-5) mol/L), indomethacin (10(-5) mol/L), hexamethonium (10(-5) mol/L), glibenclamide (10(-5) mol/L), 4-aminopyridine (10(-3) mol/L), tetraethylammonium (3 x 10(-4) mol/L), clotrimazole (10(-6) mol/L), 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) (10(-6) mol/L), and anthracene-9-carboxylate (9-AC) (10(-6) mol/L), but potentiated by bupivacain (10(-5) mol/L). A calcium-antagonizing effect of nicotine was not observed. The results suggest that nicotine-induced relaxation of the sheep's sphincter of Oddi is not mediated by the release of prostaglandins, nitric oxide (NO), or a related substance; by the activation of potassium channels or chloride channels; or by the stimulation of nicotinic cholinoceptors. Potentiation of the nicotine-induced relaxation by bupivacain indicates that blockade of sodium channels may play a role in this relaxation.     

Mechanism of reaction of myeloperoxidase with nitrite

Myeloperoxidase (MPO) is a major neutrophil protein and may be involved in the nitration of tyrosine residues observed in a wide range of inflammatory diseases that involve neutrophils and macrophage activation. In order to clarify if nitrite could be a physiological substrate of myeloperoxidase, we investigated the reactions of the ferric enzyme and its redox intermediates, compound I and compound II, with nitrite under pre-steady state conditions by using sequential mixing stopped-flow analysis in the pH range 4-8. At 15 degrees C the rate of formation of the low spin MPO-nitrite complex is (2.5 +/- 0.2) x 10(4) m(-1) s(-1) at pH 7 and (2.2 +/- 0.7) x 10(6) m(-1) s(-1) at pH 5. The dissociation constant of nitrite bound to the native enzyme is 2.3 +/- 0.1 mm at pH 7 and 31.3 +/- 0.5 micrometer at pH 5. Nitrite is oxidized by two one-electron steps in the MPO peroxidase cycle. The second-order rate constant of reduction of compound I to compound II at 15 degrees C is (2.0 +/- 0.2) x 10(6) m(-1) s(-1) at pH 7 and (1.1 +/- 0.2) x 10(7) m(-1) s(-1) at pH 5. The rate constant of reduction of compound II to the ferric native enzyme at 15 degrees C is (5.5 +/- 0.1) x 10(2) m(-1) s(-1) at pH 7 and (8.9 +/- 1.6) x 10(4) m(-1) s(-1) at pH 5. pH dependence studies suggest that both complex formation between the ferric enzyme and nitrite and nitrite oxidation by compounds I and II are controlled by a residue with a pK(a) of (4.3 +/- 0.3). Protonation of this group (which is most likely the distal histidine) is necessary for optimum nitrite binding and oxidation.     

Determination of the kinetics of deuteration of DNA.RNA hybrids by ultraviolet spectroscopy

The kinetics of the hydrogen-deuterium exchange reactions of poly(dA).poly(rU) and poly(rA).poly(dT) has been examined, at pH 7.0 and at various temperatures in the 15-35 degrees C range, by stopped-flow ultraviolet spectrophotometry. For comparison, the deuteration kinetics of poly[d(A-T)].poly[d(A-T)] and poly(rA).poly(rU) has been reexamined. At 20 degrees C, the imino deuteration (NH----ND) rates of the two hybrid duplexes were found to be 1.5 and 1.8 s-1, respectively. These are nearly equal to the imino deuteration rates of poly[d(A-T)].poly[d(A-T)] (1.1 s-1) and poly(rA).poly(rU) (1.5 s-1) but appreciably higher than that of poly(dA).poly(dT) (0.35 s-1). It has been suggested that a DNA.RNA hybrid, an RNA duplex, and the AT-alternating DNA duplex have in general higher base-pair-opening reaction rates than the ordinary DNA duplex. The amino deuteration (NH2----ND2) rates, on the other hand, have been found to be 0.25, 0.28, and 0.33 s-1, respectively, for poly(dA).poly(rU), poly(rA).poly(dT), and poly[d(A-T)].poly[d(A-T)], at 20 degrees C. These are appreciably higher than that for poly(rA).poly(rU) (0.10 s-1). In general, the equilibrium constants (K) of the base-pair opening are considered to be greatest for the DNA.RNA hybrid duplex (0.05 at 20 degrees C), second greatest for the RNA duplex (0.02 at 20 degrees C), and smallest for the DNA duplex (0.005 at 20 degrees C), although the AT-alternating DNA duplex has an exceptionally great K (0.07 at 20 degrees C). From the temperature effect on the K value, the enthalpy of the base-pair opening was estimated to be 3.0 kcal/mol for the DNA.RNA hybrid duplex.     

Analysis of a mathematical model of the effect of inhibitors on the growth of tumors

In this paper, we study a model of tumor growth in the presence of inhibitors. The tumor is assumed to be spherically symmetric and its boundary is an unknown function r=R(t). Within the tumor the concentration of nutrient and the concentration of inhibitor (drug) satisfy a system of reaction-diffusion equations. The important parameters are Lambda(0) (which depends on the tumor's parameters when no inhibitors are present), gamma which depends only on the specific properties of the inhibitor, and beta; which is the (normalized) external concentration of the inhibitor. In this paper, we give precise conditions under which there exist one dormant tumor, two dormant tumors, or none. We then prove that in the first case, the dormant tumor is globally asymptotically stable, and in the second case, if the radii of the dormant tumors are denoted by R(s)(-),R(s)(+) with R(s)(-)infinity)R(t)=R(s)(-), provided the initial radius R(0) is smaller than R(s)(+); if however R(0)R(s)(+) then the initial tumor in general grows unboundedly in time. The above analysis suggests an effective strategy for treatment of tumors.     

Effect of the method of preparation on the composition and cytotoxic activity of the essential oil of Pituranthos tortuosus

The aerial parts of Pituranthos tortuosus (Desf.) Benth and Hook (Apiaceae), growing wild in Egypt, yielded 0.8%, 0.6%, and 1.5% (v/w) of essential oil when prepared by hydrodistillation (HD), simultaneous hydrodistillation-solvent (n-pentane) extraction (Lickens-Nickerson, DE), and conventional volatile solvent extraction (preparation of the "absolute", SE), respectively. GC-MS analysis showed that the major components in the HD sample were beta-myrcene (18.81%), sabinene (18.49%), trans-iso-elemicin (12.90%), and terpinen-4-ol (8.09%); those predominent in the DE sample were terpinen-4-ol (29.65%), sabinene (7.38%), gamma-terpinene (7.27%), and beta-myrcene (5.53%); while the prominent ones in the SE sample were terpinen-4-ol (15.40%), dill apiol (7.90%), and allo-ocimene (4E,6Z) (6.00%). The oil prepared in each case was tested for its cytotoxic activity on three human cancer cell lines, i.e., liver cancer cell line (HEPG2), colon cancer cell line (HCT116), and breast cancer cell line (MCF7). The DE sample showed the most potent activity against the three human cancer cell lines (with IC50 values of 1.67, 1.34, and 3.38 microg/ml against the liver, colon, and breast cancer cell lines, respectively). Terpinen-4-ol, sabinene, gamma-terpinene, and beta-myrcene were isolated from the DE sample and subjected to a similar evaluation of cytotoxic potency; significant activity was observed.     

Composition of the essential oil of the liverwort Radula perrottetii of Japanese origin

Analysis of the essential oil of the liverwort Radula perrottetii afforded two novel viscidane diterpenes, viscida-3,9,14-triene (1), viscida-3,11(18),14-triene (2), four bisabolane sesquiterpenes, bisabola-2,6,11-triene (3), bisabola-1,3,5,7(14),11-pentaene (4), bisabola-1,3,5,7,11-pentaene (5), 6,7-epoxybisabola-2,11-diene (6), and 1-methoxy-4-(2-methylpropenyl)benzene (7) as new natural products. In addition, the known compounds bisabola-1,3,5,7(14),10-pentaene (8), ar-tenuifolene (9), alpha-helmiscapene (10), and beta-helmiscapene (11) were also isolated. Isolation was carried out by preparative gas chromatography, and the structures were established by extensive NMR analysis. This is the first finding of viscidane diterpenes in liverworts. Compounds 8, 9 and the rarely encountered eudesmane sesquiterpene hydrocarbons 10 and 11 are reported for the first time from R. perrottetii.     

Investigation of frequency of occurrence of core Y haplogroups in residents of Moscow and St. Petersburg

The collection of DNA from 239 Moscow residents and 62 St. Petersburg residents has been investigated by means of a biochip for genotyping haplogroup markers of the Y chromosome, including M130 (C), M145 (DE), P257 (G), M69 (II), U179 (I), M304 (J), M185 (L), M231 (N), M175 (O), P224 (R), L146 (R1a), and M343 (R1b). The distribution of haplogroup frequency in populations native to Moscow and St. Petersburg has been obtained. Three subsamples that vary in the duration of residence (one, two, or three generations) were compared. The increase in J, G, and R1b frequencies may be related to immigration from the Caucasus and other regions.     

三种钠尿肽抑制大鼠肺动脉平滑肌细胞增殖效应的比较

本文比较了心房钠尿肽（ＡＮＰ）、Ｃ－型钠尿肽（ＣＮＰ）、血管钠肽（ＶＮＰ）抑制肺动脉平滑肌细胞（ＰＡＳＭＣｓ）增殖的效应。用蛋白激酶Ｃ激动剂佛波酯（ＰＭＡ）刺激体外培养大鼠ＰＡＳＭＣｓ的增殖,以总蛋白含量和ＭＴＴ比色ＯＤ值为指标,观察三种钠尿肽对ＰＭＡ刺激大鼠ＰＡＳＭＣｓ增殖的影响。结果表明,ＰＭＡ（１０＾－９－１０＾－７ｍｏｌ／Ｌ）显著升高（Ｐ＜０．０５）ＰＡＳＭＣｓ的总蛋白含量和ＭＴＴＯＤ值,     

Compatibility of osmolytes with Gibbs energy of stabilization of proteins

This study led to the conclusion that naturally occurring osmolytes which are known to protect proteins against denaturing stresses, do not perturb the Gibbs energy of stabilization of proteins at 25 degrees C (DeltaG(D) degrees ) which has been shown to control the in vivo rate of degradative protein turnover (Pace et al., Acta Biol. Med. Germ 40 (1981) 1385-1392). This conclusion has been reached from our studies of heat-induced denaturation of lysozyme, ribonuclease A, cytochrome c and myoglobin in the presence of different concentrations of osmolytes, namely, glycine, proline, sarcosine and glycine-betaine. At a fixed concentration of osmolyte a heat-induced denaturation curve measured by following changes in the molar absorption coefficient of the protein, was analyzed for T(m), the midpoint of the denaturation and DeltaH(m), the enthalpy change of denaturation at T(m). Values of DeltaG(D) degrees were determined with Gibbs-Helmoltz equation using known values of T(m), DeltaH(m) and DeltaC(p), the constant-pressure heat capacity change. It has been observed that T(m) increases with the osmolyte concentration, whereas DeltaG(D) degrees remains unaffected in the presence of the osmolyte. This observation on DeltaG(D) degrees in the presence of osmolytes has been considered in the physiological context.     

Flora of planktonic microalgae of Amursky Bay, Sea of Japan

Long-term studies of the species composition of phytoplankton in Amursky Bay (Sea of Japan) carried out during the period from 1991 to 2006 revealed a total of 357 species of planktonic microalgae from eight divisions: Cyanophyta (8 species), Chrysophyta (8), Bacillariophyta (157), Cryptophyta (5), Dinophyta (143), Raphidophyta (3), Euglenophyta (11), and Chlorophyta (22 species). An annotated checklist of species is presented. In comparison with the late 1960s and early 1970s, the species richness of phytoplankton increased markedly; a greater number of bloom-forming species was recorded.     

Stages of the development of the embryos of snakes by the time of oviposition]

Embryos of 6 species of snakes--Ptyas mucosus (L.), Elaphe dione (Pall.), Psammophis lineolatum (Brandt), Natrix tesselata (Laur), Naja oxiana (EICHW.), Vipera lebetina turanica (Cernov) and V. l. obtusa--at the stage of egg laying are described morphologically. Different species of snakes are shown to lay the eggs containing embryos of different degrees of maturation. This series of transitions at the embryonic age (up to the time of egg viviparity) is connected with ecological peculiarities of different species.     

Characteristics of GABA-potentiating effect of harman

Experiments on an isolated spinal cord of rats aged 9-15 days have shown that harmane (10(-7)-10(-5) M) enhances GABA-induced (1.10(-4) M) depolarization of primary afferents and hyperpolarization of motoneurones. The GABA-potentiating action of harmane on primary afferents is depicted by a bell-shaped curve with a maximum at 10(-5) M. The action is more pronounced the higher the concentration of chlorine ions in the medium. Harmane (10(-6)-10(-4) M) enhances spontaneous neuronal activity and evoked synaptic potentials (mono- and polysynaptic potentials of the ventral and dorsal roots) at the concentrations at which it exerts a direct depolarizing action on motoneurones and primary afferents. At higher concentrations the stimulant activity of harmane (10(-5)-10(-4) M) counteracts its GABA-potentiating effects.     

Mechanism of chaperone-like activity. Suppression of thermal aggregation of betaL-crystallin by alpha-crystallin

Thermal denaturation and aggregation of beta(L)-crystallin from bovine lens have been studied using differential scanning calorimetry (DSC) and dynamic light scattering (DLS). According to the DLS data, the distribution of the beta(L)-crystallin aggregates by their hydrodynamic radius (R(h)) remains monomodal to the point of precipitating aggregates (sodium phosphate, pH 6.8; 100 mM NaCl; 60 degrees C). The size of the start aggregates (R(h,0)) and duration of the latent stage (t(0)) leading to the formation of the start aggregates have been determined from the light scattering intensity versus the hydrodynamic radius plots and the dependences of R(h) on time. The R(h,0) value remains constant at variation of the beta(L)-crystallin concentration, whereas the t(0) value increases with diminishing beta(L)-crystallin concentration. The suppression of beta(L)-crystallin aggregation by alpha-crystallin is connected with the decrease in the R(h,0) value and increase in the t(0) value. In the presence of alpha-crystallin the aggregate population is split into two components. The first component is represented by stable aggregates whose size remains constant in time. The aggregates of the other kind grow until they reach the size characteristic of aggregates prone to precipitation. The DSC data show that alpha-crystallin has no appreciable influence on thermal denaturation of beta(L)-crystallin.     

蹄叶橐吾根的化学成分研究

从蹄叶橐吾（Ligularia fischeri）的根中分离得到13个化合物,通过波谱学等方法鉴定为2-hydrox-platyphyllide（1）,liguhodgsonal（2）,nsujapone（3）,6’-亚油酰基田-胡萝卜苷（4）,Luped（5）,6,7-二羟基香豆素（6）,3-谷甾醇（7）,胡萝卜苷（8）,（25,3S,4R,12E）-N-[2’-（R）-羟基二十二碳酰基]-1,3,4-三羟基-2-氨基-二十碳-12-烯（9）,单硬脂酸甘油酯（10）,α-羟基二十四烷酸（11）,1,3-二棕榈酸甘油酯（12）,二十七烷醇（13）。其中化合物1—6为首次从该种植物中分离得到。     

Enzymology of repair of etheno-adducts

Etheno(epsilon)-adducts such as 1,N(6)-ethenoadenine (epsilon A), 3,N(4)-ethenocytosine (epsilon C), N(2),3-ethenoguanine (N(2),3-epsilon G), and 1,N(2)-ethenoguanine (1,N(2)-epsilon G) are produced in cellular DNA by two independent pathways: (i) by reaction with oxidised metabolites of vinyl chloride, 2-chloroacetaldehyde and 2-chloroethylene oxide; (ii) by endogenous processes through the interaction of lipid peroxidation (LPO)-derived aldehydes and hydroxyalkenals. They have been found in DNA isolated from human and rodent tissues. However, the levels of adducts were significantly increased by cancer risk factors contributing to lipid peroxidation and oxidative stress.The highly mutagenic and genotoxic properties of epsilon-adducts have been established in vitro by analysing steady-state kinetics of primer extension assays and in vivo by site-specific mutagenesis in mammalian cells. Therefore, the repair processes eliminating exocyclic adducts from DNA should play a crucial role in maintaining the stability of genetic information. The epsilon-adducts are eliminated by the base excision repair (BER) pathway, with DNA glycosylases being the key enzymes of this pathway. They remove epsilon-adducts from DNA by hydrolysing the N-glycosidic bond between the damaged base and deoxyribose, leaving an abasic site in DNA. The ethenobase-DNA glycosylases have been identified and their enzymatic properties described. They are specific for a given epsilon-base although they can also excise different types of modified bases, such as alkylated purines, hypoxanthine and uracil. The fact that ethenoadducts are recognised and excised with high efficiency by various DNA glycosylases in vitro suggests that these enzymes may be responsible for repair of these mutagenic lesions in vivo, and thus constitute important contributors to genetic stability.