Coping strategies and social support as moderators of occupational stress and mental health link among police personnel.

BACKGROUND: The occupation of police personnel is known to be enormously stressful. The occupational stress research shows that coping strategies and social support have a buffering effect on stress and a protective role on mental health. The present research study was set out to investigate the role of coping strategies and social support as moderating factors of the relationship between occupational stress and mental health in police personnel of Uttar Pradesh in terms of their ranking. METHODOLOGY: The present cross-sectional study was conducted using standardized questionnaires. The sample comprised a total of 300 male police personnel. Hundred constables, 100 inspectors, and 100 officers were incidentally selected from six districts of Uttar: Lucknow, Varanasi, Meerut, Raebareli, Ghaziabad, and Noida. RESULTS: Study results showed coping strategies and social support to have a moderating effect on the relationship between stress and mental health in inspectors and officers but failed to show such relationship in constables. CONCLUSION: There is the implication for the training in terms of teaching-specific active and adaptive coping strategies for the management of workplace-related stress and promotion of health and well-being in the police personnel.

Mapping genomic regions of moisture deficit stress tolerance using backcross inbred lines in wheat (Triticum aestivum L.).

Identification of markers associated with major physiological and yield component traits under moisture deficit stress conditions in preferred donor lines paves the way for marker-assisted selection (MAS). In the present study, a set of 183 backcross inbred lines (BILs) derived from the cross HD2733/2*C306 were genotyped using 35K Axiom genotyping array and SSR markers. The multi-trait, multi-location field phenotyping of BILs was done at three locations covering two major wheat growing zones of India, north-western plains zone (NWPZ) and central zone (CZ) under varying moisture regimes. A linkage map was constructed using 705 SNPs and 86 SSR polymorphic markers. A total of 43 genomic regions and QTL × QTL epistatic interactions were identified for 14 physiological and yield component traits, including NDVI, chlorophyll content, CT, CL, PH, GWPS, TGW and GY. Chromosomes 2A, 5D, 5A and 4B harbors greater number of QTLs for these traits. Seven Stable QTLs were identified across environment for DH (QDh.iari_6D), GWPS (QGWPS.iari_5B), PH (QPh.iari_4B-2, QPh.iari_4B-3) and NDVI (QNdvi1.iari_5D, QNdvi3.iari_5A). Nine genomic regions identified carrying major QTLs for CL, NDVI, RWC, FLA, PH, TGW and biomass explaining 10.32-28.35% of the phenotypic variance. The co-segregation of QTLs of physiological traits with yield component traits indicate the pleiotropic effects and their usefulness in the breeding programme. Our findings will be useful in dissecting genetic nature and marker-assisted selection for moisture deficit stress tolerance in wheat.

Mining of Indian wheat germplasm collection for adult plant resistance to leaf rust.

Leaf rust (Puccinia triticina Eriks.) is a fungal disease of wheat (Triticum spp.), which causes considerable yield loss. Adult plant resistance (APR) is one of the most sustainable approaches to control leaf rust. In this study, field-testing was carried out across ten different locations, followed by molecular screening, to detect the presence of APR genes, Lr34+, Lr46+, Lr67+ and Lr68 in Indian wheat germplasm. In field screening, 190 wheat accessions were selected from 6,319 accessions based on leaf tip necrosis (LTN), disease severity and the average coefficient of infection. Molecular screening revealed that 73% of the accessions possessed known APR genes either as single or as a combination of two or three genes. The occurrence of increased LTN intensity, decreased leaf rust severity and greater expression of APR genes were more in relatively cooler locations. In 52 lines, although the presence of the APR genes was not detected, it still displayed high levels of resistance. Furthermore, 49 accessions possessing either two or three APR genes were evaluated for stability across locations for grain yield. It emerged that eight accessions had wider adaptability. Resistance based on APR genes, in the background of high yielding cultivars, is expected to provide a high level of race non-specific resistance, which is durable.

Analogues of P and Z as Efficient Artificially Expanded Genetic Information System.

To artificially expand the genetic information system and to realize artificial life, it is necessary to discover new functional DNA bases that can form stable duplex DNA and participate in error-free replication. It is recently proposed that the 2-amino-imidazo[1,2- a]-1,3,5-triazin-4(8 H)one (P) and 6-amino-5-nitro-2(1 H)-pyridone (Z) would form a base pair complex, which is more stable than that of the normal G-C base pair and would produce an unperturbed duplex DNA. Here, by using quantum chemical calculations in aqueous medium, it is shown that the P and Z molecules can be modified with the help of electron-withdrawing and -donating substituents mainly found in B-DNA to generate new bases that can produce even more stable base pairs. Among the various bases studied, P3, P4, Z3, and Z5 are found to produce base pairs, which are about 2-15 kcal/mol more stable than the P-Z base pair. It is further shown that these base pairs can be stacked onto the G-C and A-T base pairs to produce stable dimers. The consecutive stacking of these base pairs is found to yield even more stable dimers. The influence of charge penetration effects and backbone atoms in stabilizing these dimers are also discussed. It is thus proposed that the P3, P4, Z3, and Z5 would form promiscuous artificial genetic information system and can be used for different biological applications. However, the evaluations of the dynamical effects of these bases in DNA-containing several nucleotides and the efficacy of DNA polymerases to replicate these bases would provide more insights.

Higher rate of central nervous system involvement by flow cytometry than morphology in acute lymphoblastic leukemia.

INTRODUCTION: Central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL) is diagnosed traditionally by cytopathology (CP) of the cerebrospinal fluid (CSF). Role of flow cytometry (FC) to diagnose CNS involvement has not been extensively investigated. METHODS: We aimed to detect CNS involvement in 42 ALL patients (33 B-ALL, nine T-ALL) at diagnosis by FC and comparing it with CP and to correlate it with known risk factors for CNS disease like Lactate dehydrogenase (LDH). A receiver operating characteristic curve was used to determine the cutoff of LDH to predict CSF involvement. For the analysis of categorical/quantitative variables, Fisher's exact test was used. For the analysis of continuous variables, Mann-Whitney test was used. A P value of <.05 was taken as significant. RESULTS: CP and FC were positive in five (11.9%) and 11 patients (26.14%) respectively with FC detecting a significantly higher level of involvement (P=.001). All CP-positive cases were FC positive. A LDH value of >472 U/L had a sensitivity of 61% and specificity of 62.5% for diagnosis of CSF involvement by FC. CONCLUSIONS: CSF FC detects CNS disease in ALL patients at diagnosis at a rate double than CP alone and is statistically associated with an elevated LDH level. It should be incorporated in the evaluation of CSF to detect CNS involvement.

Comparative evaluation of hormonal protocol on the performance of crossbred cattle.

A total of 60 animals (38 cows, 22 heifers) were selected and were divided into three groups of 20 animals each (containing both anoestrus and repeat breeder) in which treatment was performed for 60 days. Group I: control (farmer practice), T1 group: group I + hormone (double synch), and T2 group: group I + hormone (Estra double synch). The growth performances were measured in terms of body weight and average daily gain (ADG). Blood collection was done at the start and end of the experiment for assessment of blood biochemical, hematological, and reproductive status of the animals. Results revealed significant improvement in growth and reproductive performances in treatment group as compared to control group. Higher percentage of conception was achieved in group III (60%) followed by group II (55%). The least percentage was in group I (15%), i.e., in control group. So it was found that the effect of treating the reproductive-disordered animals with Estra double synch gave comparatively better result than double synch hormonal application.

Conformational stabilities of iminoallantoin and its base pairs in DNA: implications for mutagenicity.

The types of mutations induced by oxidatively damaged products of DNA are continuously in debate. For example, some biochemical studies have proposed that guanidinohydantoin (Gh) would induce exclusively G to C mutations, while other studies have predicted a mixture of various mutations including G to C, G to T and G to A. In addition to the nature of mutations, the exact reasons of these mutations are also not properly understood. It is suggested that Gh can easily isomerize to iminoallantoin (Ia) in a pH-dependent manner and the transition becomes complete at pH > 8. In order to understand Gh/Ia-induced mutations, we have here studied the role of the most stable tautomer of Ia in the R- and S-enantiomeric configurations in promoting mismatch base pair complexes in DNA by employing a density functional theoretical (DFT) approach. It is found that Ia can have 39 different possible tautomeric forms each in the R- and S-enantiomeric configurations, out of which the most stable tautomer would involve the deprotonation of the N1 atom and protonation of the N3 atom. The most stable tautomer of Ia can adopt three different rotameric conformations (Ia1, Ia2, and Ia3) of comparable stabilities. It is further revealed that these rotamers of Ia can interact with different bases of DNA in 88 different possible ways. However, the interaction of G with Ia3 in both the anti- and syn-conformations would be the most stable. It is further revealed that the base pairing patterns, binding energies and electronic environments of anti-Ia3:G and G:T complexes are similar. In addition to this, it is also found that the binding patterns and energies of Gh1:G and Ia3:G complexes are similar. Based on these results, it is proposed that under physiological conditions, Gh1 may be responsible for the observed G to C mutations in DNA, while in an acidic environment Ia3 may be responsible for the same mutations. This study has led to a solid foundation for further high resolution structural studies to completely unravel Ia-induced mutagenicity in DNA.

The R- and S-diastereoisomeric effects on the guanidinohydantoin-induced mutations in DNA.

Direct and indirect oxidation of guanine in DNA produces guanidinohydantoin (Gh), which is capable of inhibiting replication and inducing mutations during cellular activities. Although some biochemical studies have proposed that Gh may induce exclusively G to C mutations in DNA, other studies have predicted the occurrence of both G to C and G to T mutations. However, the exact reasons for these mutations and the dubious character of Gh in this context are not yet understood. Further, due to insufficient structural data, the electronic structure of Gh that can participate in the formation of different base pair complexes in DNA is also not known. Here, density functional theory (DFT) is used to find the most stable tautomers of Gh at the base level out of a total 112 possible tautomers and their involvement in mutagenesis is investigated by computing structures, energies and electronic properties of different base pair complexes formed between the syn- and anti-conformations of the most stable tautomer of Gh (aGh) and all the bases of DNA. It is found that aGh can coexist in R- and S-diastereoisomeric configurations. Due to the flexible guanidinium group, it can rotate about the N3-C4 bond in each of the above diastereoisomers to form two different stable conformations (aGh1 and aGh2). It is further shown that among the different base pair complexes involving aGh1, syn-aGh1:G is the most stable. This indicates that G would be easily incorporated against syn-aGh1 giving rise to G to C mutations in DNA. However, in the case of aGh2, G is the preferred base pair partner of syn-aGh2 and T is the preferred base pair partner of anti-aGh2. This implies that in addition to G to C mutations, the occurrence of aGh2 in DNA may also induce G to A mutations. Further, due to similarities between base pairing patterns and binding energies of syn-aGh1:A and syn-aGh2:A complexes with those of the T:A complex, DNA polymerases may mistakenly insert A opposite aGh1 or aGh2 by misrecognizing the latter as T. This may ultimately induce G to T mutations in DNA. However, as the constraints imposed by the DNA backbones and stacking interactions were not considered here, the possibilities of aGh2:T and aGh2:A base pairs need to be investigated experimentally. It is further found that the mutagenic character of aGh in the R- and S-diastereoisomeric forms is similar.

Monitoring potential molecular interactions of adenine with other amino acids using Raman spectroscopy and DFT modeling.

We report on the modes of inter-molecular interaction between adenine (Ade) and the amino acids: glycine (Gly), lysine (Lys) and arginine (Arg) using Raman spectroscopy of binary mixtures of adenine and each of the three amino acids at varying molar ratios in the spectral region 1550-550 cm(-1). We focused our attention on certain specific changes in the Raman bands of adenine arising due to its interaction with the amino acids. While the changes are less apparent in the Ade/Gly system, in the Ade/Lys or Ade/Arg systems, significant changes are observed, particularly in the Ade Raman bands that involve the amino group moiety and the N7 and N1 atoms of the purine ring. The ν(N1-C6), ν(N1-C2), δ(C8-H) and δ(N7-C8-N9) vibrations at 1486, 1332, 1253 and 948 cm(-1) show spectral changes on varying the Ade to amino acid molar ratio, the extent of variation being different for the three amino acids. This observation suggests a specific interaction mode between Ade and Lys or Arg, which is due to the hydrogen bonding. The measured spectral changes provide a clear indication that the interaction of Ade depends strongly on the structures of the amino acids, especially their side chains. Density functional theory (DFT) calculations were carried out to elucidate the most probable interaction modes of Ade with the different amino acids.

Mechanism of Action of Sulforaphane as a Superoxide Radical Anion and Hydrogen Peroxide Scavenger by Double Hydrogen Transfer: A Model for Iron Superoxide Dismutase.

The mechanism of action of sulforaphane as a scavenger of superoxide radical anion (O2(•-)) and hydrogen peroxide (H2O2) was investigated using density functional theory (DFT) in both gas phase and aqueous media. Iron superoxide dismutase (Fe-SOD) involved in scavenging superoxide radical anion from biological media was modeled by a complex consisting of the ferric ion (Fe(3+)) attached to three histidine rings. Reactions related to scavenging of superoxide radical anion by sulforaphane were studied using DFT in the presence and absence of Fe-SOD represented by this model in both gas phase and aqueous media. The scavenging action of sulforaphane toward both superoxide radical anion and hydrogen peroxide was found to involve the unusual mechanism of double hydrogen transfer. It was found that sulforaphane alone, without Fe-SOD, cannot scavenge superoxide radical anion in gas phase or aqueous media efficiently as the corresponding reaction barriers are very high. However, in the presence of Fe-SOD represented by the above-mentioned model, the scavenging reactions become barrierless, and so sulforaphane scavenges superoxide radical anion by converting it to hydrogen peroxide efficiently. Further, sulforaphane was found to scavenge hydrogen peroxide also very efficiently by converting it into water. Thus, the mechanism of action of sulforaphane as an excellent antioxidant has been unravelled.

Clinico-hematological profile and outcome of acute promyelocytic leukemia patients at a tertiary care center in North India.

OBJECTIVES: Acute promyelocytic leukemia (APL) is the only acute leukemia amenable to targeted therapy. However, there is limited Indian data on APL. We aimed to analyze data of APL patients treated with all trans retinoic acid (ATRA) and anthracycline based chemotherapy. MATERIALS AND METHODS: A total of 34 cases of APL were treated at our center over 4 years. Induction chemotherapy consisted of a combination of ATRA and daunorubicin. RESULTS: Most of our patients were intermediate risk (50%) followed by high risk (41.17%). Induction mortality was 14.7%. We observed a high incidence of febrile neutropenia (91%) and 50% of our patients developed ATRA syndrome. Four patients (11.76%) relapsed during follow-up (median - 15 months, range: 13-33 months). There was no correlation between risk status and death or relapse or ATRA syndrome. Median event free survival (EFS) duration was not reached however mean duration was 38.45 ± 3.84 months. Median overall survival (OS) duration was also not reached at 53 months of follow-up. The 4 year OS and EFS were 75.45% and 64.5% respectively. On multivariate analysis, only disseminated intravascular coagulation (DIC) significantly correlated with a poor OS and EFS. DISCUSSION: Our data reflects that APL remains a highly curable malignancy with good response to ATRA plus anthracycline based chemotherapy even with a greater number of high and intermediate risk patients. Only DIC during induction chemotherapy bore an impact on survival in our patients.

An experience of facility-based management of severe acute malnutrition in children aged between 6-59 months adopting the World Health Organization recommendations.

OBJECTIVE: To study the output indicators of a nutritional rehabilitation center to assess its performance. METHODS: Data of 182 children aged between 6-59 months with severe acute malnutrition in a nutritional rehabilitation center were analyzed retrospectively. Identification and treatment of severe acute malnutrition was done according to World Health Organization recommendations. RESULTS: The recovery rate, death rate, defaulter rate, mean (SD) weight gain and mean (SD) duration of stay in the nutritional rehabilitation center were 68%, 2.2%, 4.4%, 13.0 (9.0) g/kg/d, 12.7 (6.8) days, respectively. CONCLUSION: Nutritional rehabilitation centers are effective in management of severe malnutrition.

Study of hydration of sarcosine, formation of its zwitterion and their different oligomers in aqueous media: a Raman spectroscopic and theoretical study.

Raman spectra of the biologically important molecule sarcosine (SAR) (C3H7NO2) were studied experimentally in aqueous solution at different concentrations. These spectra were also calculated theoretically using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. Further, all the observed normal modes were assigned through potential energy distribution (PED). Geometry optimization of SAR produced its three conformers with slightly different energies. The lowest energy conformer of SAR was selected for a systematic solvation study wherein different numbers of water molecules (nW, n=1-9) were placed near it. In the SAR-9W complex, the SAR molecule is located almost at the center of the cage of 9 water molecules. Geometries of different oligomers of SAR (dimer, trimer, tetramer and pentamer) were also optimized in aqueous media taking the input structures from crystallographic data and using the polarizable continuum (PCM). Proton transfer required for the formation of the zwitterionic form of SAR was found to occur when the number of water molecules in the first hydration shell was six or more.

Polyradicals of polycyclic aromatic hydrocarbons as finite size models of graphene: highly open-shell nature, symmetry breaking, and enhanced-edge electron density.

Properties of polyradicals (all CH bonds dissociated) of benzene and certain polycyclic aromatic hydrocarbons (PAHs) were studied. The occurrence of symmetry breaking is revealed in going from benzene and the PAHs to their polyradicals. Polyradicals would serve as finite size models of graphene with unpassivated edges in a more realistic way than the PAHs. Monoradicals (one CH bond dissociated) of benzene and all of the PAHs and higher radicals of benzene and one PAH (two to all CH bonds successively dissociated) were also investigated. Reliability of the methodology employed was ascertained by a comparison of our calculated single CH bond dissociation energy of benzene with the available previous experimental and theoretical results. Besides ground-state geometries, the aspects studied include single and successive CH bond dissociation energies, and electron density, molecular electrostatic potential (MEP), and spin density distributions. All of the monoradicals studied were found to have doublet spin multiplicity, while polyradicals with 4 to 16 rings and zigzag or mixed-type edges were found to have spin multiplicities varying from triplet to 11et. Bond lengths and bond angles of rings located at the edges are appreciably modified in going from PAHs to polyradicals. Electron density and spin density are found to be enhanced at the edges of monoradicals and polyradicals of PAHs, as found previously for PAHs. However, MEP maps of polyradicals have significantly different features from those of monoradicals and PAHs, which has a significant implication.

Biosorption of arsenic (III) from aqueous solution by living cells of Bacillus cereus.

In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30 ± 2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient) >0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3).

Biosorption of As(V) from aqueous solutions by living cells of Bacillus cereus.

In this work, the biosorption of As(V) from aqueous solutions by living cells of Bacillus cereus has been reported. The batch biosorption experiments were conducted with respect to biosorbent dosage 0.5 to 15 g/L, pH 2 to 9, contact time 5 to 90 min, initial concentration 1 to 10 mg/L and temperature 10 to 40 °C. The maximum biosorption capacity of B. cereus for As(V) was found to be 30.04 at pH 7.0, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30 ± 2 °C. Biosorption data were fitted to linearly transformed Langmuir isotherms with R(2) (correlation coefficient) >0.99. Bacillus cereus cell surface was characterized using AFM and FTIR. The metal ions were desorbed from B. cereus using both 1 M HCl and 1 M HNO(3). The pseudo-second-order model was successfully applied to predict the rate constant of biosorption.

Formation of ring-opened and rearranged products of guanine: mechanisms and biological significance.

DNA damage by endogenous and exogenous agents is a serious concern, as the damaged products can affect genome integrity severely. Damage to DNA may arise from various factors such as DNA base modifications, strand break, inter- and intrastrand crosslinks, and DNA-protein crosslinks. Among these factors, DNA base modification is a common and important form of DNA damage that has been implicated in mutagenesis, carcinogenesis, and many other pathological conditions. Among the four DNA bases, guanine (G) has the smallest oxidation potential, because of which it is frequently modified by reactive species, giving rise to a plethora of lethal lesions. Similarly, 8-oxo-7,8-dihydroguanine (8-oxoG), an oxidatively damaged guanine lesion, also undergoes various degradation reactions giving rise to several mutagenic species. The various products formed from reactions of G or 8-oxoG with different reactive species are mainly 2,6-diamino-4-oxo-5-formamidopyrimidine, 2,5-diamino-4H-imidazolone, 2,2,4-triamino-5-(2H)-oxazolone, 5-guanidino-4-nitroimidazole, guanidinohydantoin, spiroiminodihydantoin, cyanuric acid, parabanic acid, oxaluric acid, and urea, among others. These products are formed from either ring opening or ring opening and subsequent rearrangement. The main aim of this review is to provide a comprehensive overview of various possible reactions and the mechanisms involved, after which these ring-opened and rearranged products of guanine would be formed in DNA. The biological significance of oxidatively damaged products of G is also discussed.

Scavenging mechanism of curcumin toward the hydroxyl radical: a theoretical study of reactions producing ferulic acid and vanillin.

Curcumin is known to be an antioxidant, as it can scavenge free radicals from biological media. A sequence of H-abstraction and addition reactions involving up to eight OH radicals and curcumin or its degradation products leading to the formation of two other antioxidants, namely, ferulic acid and vanillin, was studied. Single electron transfer from curcumin to an OH radical was also studied. All relevant extrema on the potential energy surfaces were located by optimizing geometries of the reactant and product complexes, as well as those of the transition states, at the BHandHLYP/6-31G(d,p) level of density functional theory in the gas phase. Single-point energy calculations were also performed in the gas phase at the BHandHLYP/aug-cc-pVDZ and B3LYP/aug-cc-pVDZ levels of theory. Solvent effects in aqueous media were treated by performing single-point energy calculations at all of the above-mentioned levels of theory employing the polarizable continuum model and the geometries optimized at the BHandHLYP/6-31G(d,p) level in the gas phase. A few reaction steps were also studied by geometry optimization in aqueous media, and the thus-obtained Gibbs free energy barriers were similar to those obtained by corresponding single-point energy calculations. Our calculations show that the hydrogen atom of the OH group attached to the phenol moiety of curcumin would be most efficiently abstracted by an OH radical, in agreement with experimental observations. Further, our study shows that OH addition would be most favored at the C10 site of the heptadiene chain. It was found that curcumin can serve as an effective antioxidant.

Quantum theoretical study of cleavage of the glycosidic bond of 2'-deoxyadenosine: base excision-repair mechanism of DNA by MutY.

The enzyme adenine DNA glycosylase, also called MutY, is known to catalyze base excision repair by removal of adenine from the abnormal 2'-deoxyadenosine:8-oxo-2'-deoxyguanosine pair in DNA. The active site of the enzyme was considered to consist of a glutamic acid residue along with two water molecules. The relevant reaction mechanism involving different barrier energies was studied theoretically. Molecular geometries of the various molecules and complexes involved in the reaction, e.g., the reactant, intermediate, and product complexes as well as transition states, were optimized employing density functional theory at the B3LYP/6-31G(d,p) level in the gas phase. It was followed by single-point energy calculations at the B3LYP/AUG-cc-pVDZ, BHandHLYP/AUG-cc-pVDZ, and MP2/AUG-cc-pVDZ levels in the gas phase. Single-point energy calculations were also carried out at the B3LYP/AUG-cc-pVDZ and BHandHLYP/AUG-cc-pVDZ levels in aqueous media as well as in the solvents chlorobenzene and dichloroethane. For the solvation calculations, the integral equation formalism of the polarizable continuum model (IEF-PCM) was employed. It is found that glutamic acid along with two water molecules would effectively cleave the glycosidic bond of adenosine by a new two-step reaction mechanism proposed here which is different from the three-step mechanism proposed by other authors earlier regarding the working mechanism of MutY.

Hybridization-displaced charges for amino-acids: a new model using two point charges per atom along with bond-center charges.

A new charge distribution is proposed for the amino acids where each atom is associated with two point charges while each bond center is associated with one point charge. Centroids of charges arising due to atomic orbital hybridization called hybridization-displaced charges (HDC) and those located at the atomic sites and bond centers obtained by a modified form of the Mulliken scheme were combined. The density matrix calculations required for this analysis were performed at the B3LYP/6-31G** level of density functional theory. The combination of HDC centroids with the modified Mulliken charges was found to yield dipole moments and surface molecular electrostatic potentials (MEP) of the amino acids in good agreement with those obtained by rigorous DFT calculations or those obtained using the MEP-fitted CHelpG charges. This study shows that the combination of HDC centroids with the modified Mulliken charges is significantly superior to the conventional Mulliken charges.