Nutrigenomics: SNPs correlated to minerals' deficiencies

Abstract

Nutrigenetics and nutrigenomics are two interrelated fields that explore the influence of genetic diversity on nutrient responses and function. While nutrigenetics investigates the effects of hereditary ge-netic variations on micronutrient metabolism, nutrigenomics examines the intricate relationship between diet and the genome, studying how genetic variants impact nutrient intake and gene expression. These disciplines offer valuable insights into predicting and managing chronic diseases through personalized nutritional approaches. Nutrigenomics employs cutting-edge genomics technologies to study nutrient-genome interactions. Key principles involve genetic variability among ethnic groups, affecting nutrient bioavailability and metabolism, and the influence of dietary choices based on cultural, geographic, and socioeconomic factors. Polymorphisms, particularly single-nucleotide polymorphisms (SNPs), significantly influence gene activity and are associated with specific phenotypes that are related to micronutrient deficiencies. Minerals are inorganic elements, vital for various physiological functions. Understanding the SNPs associated with mineral deficien-cies is crucial for assessing disease risk and developing personalized treatment plans. This knowledge can inform public health interventions, targeted screening programs, educational campaigns, and fortified food products to address deficiencies effectively. Nutrigenomics research has the potential to revolutionize clinical and nutritional practices, providing personalized recommendations, enhancing illness risk assessment, and advancing public health initiatives. Despite the need for further research, harnessing nutrigenomics' potential can lead to more focused and efficient methods for preventing and treating mineral deficiencies.

Nutrigenomics: SNPs Correlated to Lipid and Carbohydrate Metabolism

Background

Nutrigenomics - the study of the interactions between genetics and nutrition - has emerged as a pivotal field in personalized nutrition. Among various genetic variations, single-nucleotide polymorphisms (SNPs) have been extensively studied for their probable relationship with metabolic traits.

Methods

Throughout this review, we have employed a targeted research approach, carefully handpicking the most representative and relevant articles on the subject. Our methodology involved a systematic review of the scientific literature to ensure a comprehensive and accurate overview of the available sources.

Results

SNPs have demonstrated a significant influence on lipid metabolism, by impacting genes that encode for enzymes involved in lipid synthesis, transport, and storage. Furthermore, they have the ability to affect enzymes in glycolysis and insulin signaling pathways: in a way, they can influence the risk of type 2 diabetes. Thanks to recent advances in genotyping technologies, we now know numerous SNPs linked to lipid and carbohydrate metabolism. The large-scale studies on this topic have unveiled the potential of personalized dietary recommendations based on an individual's genetic makeup. Personalized nutritional interventions hold promise to mitigate the risk of various chronic diseases; however, translating these scientific insights into actionable dietary guidelines is still challenging.

Conclusions

As the field of nutrigenomics continues to evolve, collaborations between geneticists, nutritionists, and healthcare providers are essential to harness the power of genetic information for improving metabolic health. By unraveling the genetic basis of metabolic responses to diet, this field holds the potential to revolutionize how we approach dietary recommendations and preventive healthcare practices.

Bioetics Issues of Artificial Placenta and Artificial Womb Technology

Abstract

The worldwide infertility crisis and the increase in mortality and morbidity among infants, due to preterm births and associated complications, have stimulated research into artificial placenta (AP) and artificial womb (AW) technology as novel solutions. These technologies mimic the natural environment provided in the mother's womb, using chambers that ensure the supply of nutrients to the fetus and disposal of waste substances through an appropriate mechanism. This review aims to highlight the background of AP and AW technologies, revisit their historical development and proposed applications, and discuss challenges and bioethical and moral issues. Further research is required to investigate any negative effects of these new technologies, and ethical concerns pertaining to the structure and operation of this newly developed technology must be addressed and resolved prior to its introduction to the public sphere.

Human Cloning: Biology, Ethics, and Social Implications

Abstract

This scholarly article delves into the multifaceted domains of human cloning, encompassing its biological underpinnings, ethical dimensions, and broader societal implications. The exposition commences with a succinct historical and contextual overview of human cloning, segueing into an in-depth exploration of its biological intri-cacies. Central to this biological scrutiny is a comprehensive analysis of somatic cell nuclear transfer (SCNT) and its assorted iterations. The accomplishments and discoveries in cloning technology, such as successful animal cloning operations and advances in the efficiency and viability of cloned embryos, are reviewed. Future improvements, such as reprogramming procedures and gene editing technology, are also discussed. The discourse extends to ethical quandaries intrinsic to human cloning, entailing an extensive contemplation of values such as human dignity, autonomy, and safety. Furthermore, the ramifications of human cloning on a societal plane are subjected to scrutiny, with a dedicated emphasis on ramifications encompassing personal identity, kinship connections, and the fundamental notion of maternity. Culminating the analysis is a reiteration of the imperative to develop and govern human cloning technology judiciously and conscientiously. Finally, it discusses several ethical and practical issues, such as safety concerns, the possibility of exploitation, and the erosion of human dignity, and emphasizes the significance of carefully considering these issues.

In Memory of Professor Derek Pheby

Abstract

Professor Derek Pheby's passing in November 2022 marked a profound loss for the scientific community. Professor Derek Pheby, a stalwart figure in the fields of autoimmune diseases and bioethics, was known for his dedication to scientific research and patients' support, particularly for those affected by paraneoplastic autoimmune syndromes. Professor Pheby made significant contributions to research, especially about Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). His leadership of the ME Biobank and scientific coordination of EUROMENE demonstrated his commitment to pushing boundaries and fostering international collaborations. Professor Pheby's scientific work addressed various aspects of ME/CFS, from physician education to patient needs, the development of a post-mortem tissue bank, and effective treatments. Beyond his medical career, Professor Pheby was a crucial member of the Independent Ethics Committee of MAGI, he was a poet, humanitarian, and advocate for child protection. His generosity and boundless spirit left an enduring legacy, fostering innovative research in the pursuit of combating autoimmune diseases.

Nutrigenomics: SNPs correlated to detoxification, antioxidant capacity and longevity

Abstract

Nutritional genomics, also known as nutrigenomics, is the study of how a person's diet and genes interact with each other. The field of nutrigenomics aims to explain how common nutrients, food additives and preservatives can change the body's genetic balance towards either health or sickness. This study reviews the effects of SNPs on detoxification, antioxidant capacity, and longevity. SNPs are mutations that only change one nucleotide at a specific site in the DNA. Specific SNPs have been associated to a variety of biological processes, including detoxification, antioxidant capacity, and longevity. This article mainly focuses on the following genes: SOD2, AS3MT, CYP1A2, and ADO-RA2A (detoxification); LEPR, TCF7L2, KCNJ11, AMY1, and UCP3 (antioxidant capacity); FOXO3 and BPIFB4 (longevity). This review underlines that many genes-among which FOXO3, TCF7L2, LEPR, CYP1A2, ADORA2A, and SOD2-have a unique effect on a person's health, susceptibility to disease, and general well-being. Due to their important roles in numerous biological processes and their implications for health, these genes have undergone intensive research. Examining the SNPs in these genes can provide insight into how genetic variants affect individuals' responses to their environment, their likelihood of developing certain diseases, and their general state of health.

Quantitative structure–activity relationships and design of thymine-like inhibitors of thymidine monophosphate kinase of Mycobacterium tuberculosis with favourable pharmacokinetic profiles

We have designed new potent inhibitors of thymidine monophosphate kinase of Mycobacterium tuberculosis (TMPK_mt) using structure-based molecular design.

Molecular aspects of a novel HLA-A*02 allele (A*0297): the first HLA class I allele mutated at codon 232

We describe a new HLA-A*02 allele, identified in a cord blood unit and in her mother. Nucleotide sequence analysis showed the presence of a new HLA-A*02 allele identical to HLA-A*02010101 except for a non-synonymous nucleotide exchange in exon 4 modifying codon 232 from GAG (Glu) to GAC (Asp). No other human leucocyte antigen class I allele sequenced so far shows this triplet at codon 232. The amino acid exchange affects a position that is part of the membrane proximal domain of class I major histocompatibility complex (MHC), designated alpha 3, and involved in the interaction with CD8 molecule. Using molecular modelling approach, the interactions between different subunits of the native and mutated forms of MHC-I resulted in relevant changes.

Combinatorial chemistry and high-throughput screening in drug discovery: different strategies and formats

Different strategies for the discovery of novel leads interacting with therapeutically relevant targets are thoroughly presented and discussed, using also three recent examples. Emphasis is given to approaches which do not require extensive resources and budgets, but rather prove how cleverness and creativity can provide active compounds in drug discovery.

A glucose/hydrogen peroxide biofuel cell that uses oxidase and peroxidase as catalysts by composite bulk-modified bioelectrodes based on a solid binding matrix

An improved composite bulk-modified bioelectrode setup based on a solid binding matrix (SBM) has been used to develop a glucose/hydrogen peroxide biofuel cell. Fuel is combined through a catalytically promoted reaction with oxygen into and oxidized species and electricity. The present work explores the feasibility of a sugar-feed biofuel cell based on SBM technology. The biofuel cell that utilizes mediators as electron transporters from the glucose oxidation pathway of the enzyme directly to electrodes is considered in this work. The anode was a glucose oxidase (GOx, EC 1.1.3.4)/ferrocene-modified SBM/graphite composite electrode. The cathode was a horseradish peroxidase (HRP, EC 1.11.1.7)/ferrocene-modified SBM/graphite composite electrode. The composite transducer material was layered on a wide polymeric surface to obtain the biomodified electrodic elements, anodes and cathodes and were assembled into a biofuel cell using glucose and H(2)O(2) as the fuel substrate and the oxidizer. The electrochemical properties and the characteristics of single composite bioelectrodes are described. The open-circuit voltage of the cell was 0.22 V, and the power output of the cell was 0.15 microW/cm(2) at 0.021 V. The biofuel cell proved to be stable for an extended period of continuous work (30 days). The reproducibility of the biotransducers fabrication was also investigated. In addition, an application of presented biofuel cell, e.g. the use of hydrolyzed corn syrup as renewable biofuels, was discussed.

Molecular dynamics study on the conformational stability of laminaran oligomers in various solvents

Solution conformations of the (1-->3)-beta-D-glucan laminaran have been investigated by means of molecular mechanics and molecular dynamics simulations in three solvents: water, dimethylformamide, and dimethyl sulfoxide. Conformational analysis of solvated laminarabiose was carried out to study the effect of specific solute-solvent interactions upon reactive hydroxyl groups. Dynamic trajectories of solvated laminarabiose have been interpreted in terms of average glycosidic-linkage conformation, hydrogen-bonding pattern, and coordination by solvent molecules. The analysis of radial distribution functions, coordination functions, mean residency times, and time correlation functions derived from the simulation trajectories furnished the necessary insight. The results have been used to assess the steric accessibility of laminaran-C4-OH and -C6-OH hydroxyl groups in the considered solvents and to rationalize corresponding earlier experimental observations. The experiments demonstrated that reaction equilibrium during chemical modification of laminaran oligomers with 2,2-dimethoxypropane involving the laminaran-C4-OH and -C6-OH hydroxyl groups significantly depended on the solvent used.

Overview of remediation technologies for persistent toxic substances

This paper gives a review of established and emerging technologies for the treatment of wastes and soils contaminated by Persistent Toxic Substances which include the Persistent Organic Pollutants. The technologies are classified as biological, physico-chemical, and thermal treatments, describing main unit operations and comparing technical, social and environmental limitations, including some potential risks and environmental impacts. Estimated overall costs, cleanup times, reliability, and maintenance levels are also presented in order to assess advantages and limitations of each technology.

Design and synthesis of novel [60]fullerene derivatives as potential HIV aspartic protease inhibitors

[structure] Two water-soluble fullerene derivatives have been computer-designed and synthesized. They may exhibit interesting anti-HIV activity owing to the presence of two ammonium groups strategically located on the spheroid surface.

Selective and sensitive biosensor for theophylline based on xanthine oxidase electrode

Milk and microbial xanthine oxidases (XOs) were used for the construction of amperometric enzyme electrodes. Substrate specificity differences of these enzymes were studied. Of the two enzymes, only the microbial XO was found to oxidize theophylline, but not theobromine and caffeine. The substrate specificity of microbial XO was affected by pH, where the optimum for xanthine was 5.5, while for theophylline it was in the range from 6.5 to 8.5. The theophylline biosensor showed a low detection limit of 2 x 10(-7) M and signal linearity up to 5 x 10(-5) M. The sensitivity of the microbial XO electrode to theophylline could be selectively eliminated by immersion in alkaline phosphate solution, thus allowing for the construction of a blank electrode for differential measurements. The feasibility of this approach has been demonstrated by the determination of free (unbound) and total theophylline in blood samples. The biosensor exhibited good operational (>6 h) and shelf (>3 months) stability when trehalose was used as a stabilizer of the biocatalytic layer.

The structure of gellan in dilute aqueous solution

A full assignment of high-field nmr spectra of gellan was obtained in dilute aqueous solution by performing a series of selective one-dimensional nmr experiments. The observed nuclear Overhauser effects (NOEs) cannot be interpreted assuming that each sugar residue is intrinsically rigid and in a chair conformation. In fact, the rhamnose residue gives strong NOE contacts coherent only with an equilibrium involving both a chair as well as a boat (or a hemiboat) conformation. Molecular dynamic calculations performed on a heptamer with a central rhamnose support the above finding, and show a structure based on a very stiff single chain in which it is present a flipping of the rhamnose residue. At low temperatures (5-20 degrees C) in very dilute solutions (0.018 mg/mL) nmr spectra show a splitting of the resonance due to the methyl group of rhamnose residue, thus confirming the presence of a slow equilibrium among different conformers.

Aspartic protease inhibitors. An integrated approach for the design andsynthesis of diaminodiol-based peptidomimetics

Aspartic proteases play key roles in a variety of pathologies, including acquired immunodeficiency syndrome. Peptidomimetic inhibitors can act as drugs to combat these pathologies. We have developed an integrated methodology for preparing human immunodeficiency virus (HIV)-1 aspartic protease diaminodiol inhibitors, based on a computational method that predicts the potential inhibitory activity of the designed structures in terms of calculated enzyme-inhibitor complexation energies. This is combined with a versatile synthetic strategy that couples a high degree of stereochemical control in the central diaminodiol module with complete flexibility in the choice of side chains in the core and in flanking residues. A series of 23 tetrameric, pentameric and hexameric inhibitors, with a wide range of calculated relative complexation energies (-47.2 to +117 kJ.mol-1) and predicted hydrophobicities (logPo/w = 1.8-8.4) was thus assembled from readily available amino acids and carboxylic acids. The IC50 values for these compounds ranged from 3.2 nM to 90 microM, allowing study of correlations between structure and activity, and individuation of factors other than calculated complexation energies that determine the inhibition potency. Multivariable regression analysis revealed the importance of side-chain bulkiness and rigidity at the P2, P2' positions, suggesting possible improvements for the prediction process used to select candidate structures.

Computational design of new cyclic urea inhibitors for improved binding of HIV-1 aspartic protease

We report in this paper the design, by means of computational techniques, of new cyclic urea inhibitors of the HIV aspartic protease. The relationship between the complexation energies of the enzyme with known inhibitors and the experimentally determined log K(i) have been studied and used to predict inhibition constants for new inhibitors.

Stereoselective synthesis of non symmetric dihydroxyethylene dipeptide isosteres via epoxy alcohols derived from alpha-amino acids

(1R,2R,3S,4S)-4-Amino-3-hydroxy-1,2-epoxybutanes, accessible in four steps from L-aminoesters, react regio- and stereoselectively with diethyl aluminum cyanide to give (1R,2S,3S,4S)-4-amino-2,3-dihydroxynitriles. Hydrolysis yields hydroxylactones equivalent to 2,3-dihydroxy-4-aminoacids. The sequence provides a novel approach to dihydroxyethylene isosteres potentially useful for new HIV-protease inhibitors.

Amperometric biosensors based on solid binding matrices applied in food quality monitoring

Solid binding matrix (SBM) based composite transducers have been used for development of series of multibiosensor systems applicable in various fields. Here we present two hybrid three-channel multibiosensors for simultaneous amperometric operation in food quality control, i.e. glucose/fructose/ethanol multibiosensor, based on glucose oxidase/fructose dehydrogenase/alcohol dehydrogenase surface-modified enzyme electrodes and L-lactate/L-malate/sulfite multibiosensor, based on L-lactate dehydrogenase/L-malate dehydrogenase/sulfite oxidase surface-modified enzyme electrodes. Different parameters have been studied in order to optimize the response of the multibiosensor systems. The multibiosensor showed a good sensitivity, linear range and storage stability. The multibiosensors were used for the determination of glucose, fructose, ethanol, L-lactate, L-malate and sulfite in samples of wine, resulting in a good agreement with data certified by the supplier. Comparison of various designs, surface-modified, bulk-modified and thick-cover, of SBM based biosensors is studied on the example of fructose biosensor.

Rational design of inhibitors for drug-resistant HIV-1 aspartic protease mutants

This report describes a method for the assessment of inhibitor binding affinities to wild type HIV-1 aspartic protease and to its drug-resistant mutant forms. We have elaborated a refined method for molecular modeling of the 3D structures of mutant enzymes and enzyme-inhibitor complexes based on the crystal structure of the wild type form, which employs a full thermodynamic cycle. Model complexes of four HIV-1 aspartic protease mutants with ten analogs of the A77003 inhibitor were considered. Predictions of inhibition efficiency, resistance potential, and hydrophilicity of the redesigned A77003 analogs were obtained by employing molecular mechanics for the evaluation of enzyme-inhibitor complexation energy and the polarizable continuum model for the estimation of solvent effects. Simple qualitative indicators for structural modifications aimed at overcoming the emergence of HIV resistance to protease inhibitors and at increasing the bioavailability of pseudopeptide inhibitors are examined. A semi-quantitative method for the description of enzyme-ligand binding and its implications for the rational design of inhibitors with higher binding affinity towards emerging HIV PR mutants is presented.

A computational study of the resistance of HIV-1 aspartic protease to the inhibitors ABT-538 and VX-478 and design of new analogues

Recent experimental findings with HIV-1 protease (HIV-1 PR) mutants containing variations at four residues, M46I, L63P, V82T and I84V, have shown that only mutants containing the latter two exhibit cross resistance to the inhibitors ABT-538 and VX-478. The V82T and I84V modifications in fact concern residues in the active site while the other two are in the flap (M46I) and hinge (L63P) domains of the enzyme. We have modelled the M46I/L63P, V82T/I84V and M46I/L63P/ V82T/I84V (4X) mutants of HIV-PR and computed their complexation energies with these two inhibitors. A good correlation was found between these complexation energies and the trend in published inhibition constants for these inhibitors. Reasons for the decrease in binding affinities with the two critical mutants (V82T/I84V and 4X) have also been elucidated in detail. Based on these findings, we have designed several analogues of ABT-538 and VX-478, some of which show a better calculated binding affinity towards both mutant and wild type PR.

Modelling of the 3-D structure of IFN-alpha-k and characterization of its surface molecular properties

The 3-D structure of IFN-alpha-k (one of the alpha-interferon family) was constructed and optimized by molecular modelling starting from the X-ray structure of IFN-beta. The molecular surface of the optimized 3-D structure of IFN-alpha-k was then evaluated and characterized for its hydrophobicity/hydrophilicity. The structure of IFN-alpha-k was completed with its first segment (23 amino acid residues) called signal peptide. The 3-D structure of this segment was predicted to be in helical form bonded to the core by one loop. It was found that the complete structure of IFN-alpha-k can exist in at least two main conformations as far as the orientation of the signal peptide is concerned, i.e. in the open form (in which the signal peptide is directed outward of the 'body' of the molecule) and the closed form (where the signal peptide is aligned with the body). The relative stability of these forms strongly depends on the stabilization by the environment (e.g. by solvation) due to the prevailing hydrophilicity of the body and hydrophobic character of the signal peptide.

Development of pseudopeptide inhibitors of HIV-1 aspartic protease: analysis and tuning of the subsite specificity

HIV-1 aspartic protease (PR) is a promising target for acquired immunodeficiency syndrome (AIDS) therapy, and the development of PR inhibitors can be accelerated by computer-aided design methods. We describe an approach for the design of new inhibitors, based on the modification of a known reference inhibitor, and the calculation of relative binding energies, taking into account contributions from all species in the binding equilibrium (inhibitor, PR and inhibitor/PR complex), as well as their solvation. This allows for a rational selection of new structures that are likely to have increased inhibition potency. We have analyzed reduced amide bond hexapeptides (Ac-P3-P2-P1-phi[CH2-NH]-P1'-P2-P3'-NH2), based on the structure of the known inhibitor MVT-101. A maximum gain in binding energy (approximately -55 kcal/mol) is observed when Phe or Tyr are present in positions P1 and P1', Glu in position P2' and aromatic residues (Phe, Trp or Tyr) in positions P3 and P3', while, in general, the presence of positively charged residues is destabilizing. This specificity is explained in terms of the interaction of individual inhibitor residues with proximal and distal PR residues. The validity of this computational approach has been confirmed by solid-phase synthesis of several of the designed pseudopeptides, followed by in vitro enzyme inhibition assaying. The best candidate structures show IC50 values in the low nanomolar range.

Conformational analysis of segments of oxidized cellulose. Part I: Molecular modelling of glucuronic acid dimers considering the effect of counter-ions and a polar environment

Conformational analysis of various forms of glucuronic acid dimers as the model structures of oxidized cellulose has been performed using molecular mechanics with a CVFF force field. The effects of ionization of carboxyl groups, ion pairing with explicit consideration of counter-ions (Na+, Mg2+) and the implicit inclusion of a solvent effect via the dielectric constant, epsilon, have been simulated. The non-ionized glucuronic acid dimer shows conformational behaviour similar to that of unoxidized cellobiose. The ionization of COOH groups leads to strong destabilization of C and D conformers (with both COO- groups on the same side of the molecule), while complexation with counter-ions leads to strong stabilization of these forms which yield highly wound low-pitch helices. An increase in the solvent polarity has an attenuating effect on the behaviour described above.

Immunoreactivity of chimeric proteins carrying the HIV-1 epitope IGPGRAF. Correlation between predicted conformation and antigenicity

Sera from HIV-1 infected individuals were examined for their reactivity to the principal neutralizing domain, IGPGRAF sequence, of the V3-loop of HIV-1. Four hybrid proteins carrying this sequence inserted in four different outer loops of a protein that makes up the capsid of an insect virus were used as antigen in a Western blot assay for this survey. All the four antigens showed different activity: sera that recognise all antigens to sera that reacted with only one of them. Competition experiments indicated that the antibodies recognised these proteins with different affinity. Molecular modelling of the hybrid proteins predicted that the inserted sequence adopted different conformations in each position. Comparison of predicted most stable conformations for IGPGRAF indicated that there is a close relationship between conformational similarity to a V3-loop reference structure and the degree of reactivity with sera.

Molecular modeling of acrylamide derivatives: the case of N-acryloylaminoethoxyethanol versus acrylamide and trisacryl

Molecular mechanics (for evaluation of total energies of individual structures of monomers and oligomers) and molecular dynamics (for evaluating dynamic dependencies of structural features) were used for obtaining information on some unique chemical behavior of a novel N-substituted acrylamide (N-acryloylaminoethoxyethanol; AAEE) vs. conventional acrylamide and trisacryl (N-acryloyl-2-amino-2-hydroxymethyl-1,3-propane diol, an extremely hydrophilic derivative; Tris-A). As free monomers, Tris-A degrades with zero-order and acrylamide with first-order kinetics, whereas AAEE is highly resistant to hydrolysis. It is found that Tris-A (and its dideoxy derivative) is constantly forming hydrogen bonds between the -OH groups and the carbonyl of the amido group (bond distances of 1.64 to 1.70 A); this activates a mechanism of "N-O acyl transfer" which leads to quick degradation of the amido bond even under mildly alkaline conditions. Conversely, AAEE (which also contains an omega-OH group increasing its hydrophilicity) has no tendency to form H-bonds with the amido carbonyl, thus being resistant to the above degradation mechanism. In fact, the oxygen in the ethoxy moiety of the N-substituent chain acts as a preferential partner for H-bond formation with the omega-OH group. In the oligomeric state, it is found that Tris-A (tetrameric and dodecameric structures were simulated) tends to form inter-residue H-bonds (approximately parallel to the growing chain) competing with the intra-residue H-bonds (folding onto the amido carbonyl and approximately perpendicular to the oligomer chain), thus greatly increasing its stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Configurational stability and molecular dynamics of acetal-linked pyruvate substituents in polysaccharides

Pyruvate groups occur naturally in many microbial polysaccharides as nonsaccharidic components and significantly affect their physicochemical and biological properties. The configuration of the acetal carbon of pyruvate groups is mainly influenced by the favoured equatorial orientation of the methyl group. Evaluation of conformational energies has been carried out to assess the relative stabilities of the R and S isomers as a function of configuration and torsional angles for several residue models, including methyl 4,6-O-(1-carboxyethylidene)-alpha-D-galactopyranoside (1). Different levels of theoretical approach are used ranging from ab initio, semiempirical (AM1), and molecular mechanics (MM) methods up to molecular dynamics (MD). The higher stability of the isomer R of 1 was demonstrated by all of the methods used, thus giving full agreement with the NMR data on the natural compounds.

Hybrid biosensor for the determination of lactose

Genetically manipulated bacteria Escherichia coli K-12 recombinant PQ-37 and glucose oxidase (EC 1.1.3.4) were used for the construction of a hybrid lactose sensor because of the hyperproduction of beta-galactosidase (EC 3.2.1.23) by E. coli effected by a genotoxic agent. The biocatalytic layer was prepared by coimmobilization of the E. coli cells with glucose oxidase on the nylon network via glutardialdehyde and fixed to the Clark oxygen electrode. The influence of pH, temperature, and concentration of activators of beta-galactosidase on the sensor response was tested. Analyses of milk products were completed without any special pretreatment of the samples. The contents of lactose determined by hybrid sensor agree with conventional photometric measurements. Standard relative deviation is less than 3% for all samples. The half-life of operational stability is 30 days.

Relationships between structure of 5-nitro-2-furylethylenes and their SOS-function-inducing activities in Escherichia coli

The SOS-function-inducing activities of 36 furylethylenes were characterized in Escherichia coli K12. The induction of the SOS function was assayed by monitoring the beta-galactosidase activity in the sulA::lacZ fusion strain PQ 37. To correct for the inhibitory effects of test compounds on mRNA or protein synthesis, the level of the constitutive alkaline phosphatase was assayed in parallel. Tested furylethylenes included nine alkylesters and eleven N-alkylamides of 5-nitro-2-furylacrylic acid (NFAA) and fourteen derivatives differing not only in substituents at exocyclic double bond, but also in the position 5 of the furan ring. The induction of the SOS-function by the derivatives depends on the presence of 5-nitrofuran centre in their molecule; side chains in the position 2 modify the degree of SOS response. SOS-inducing potency of n-alkyl congeners decreases with increasing lipophilicity. Effect of derivatives with branched alkyl substituents is lower than expected from the behavior of the n-alkyl homologues. All derivatives with positive effect on SOS-function in E. coli show mutagenic activity on Salmonella typhimurium TA98 in Ames test.

Theoretical study on the alkylation and protonation of the nucleic acid bases

Protonation and alkylation by H+, CH3+ and C2H5+ of nucleic acid bases (cytosine, thymine, uracil, adenine and guanine) have been studied. Different theoretical approaches, namely semi-empirical MINDO/3 and ab initio calculations, have been compared, together with experimental values. The necessity of supermolecular approach to the study of alkylation is indicated. It is also shown that changes of size of attacking agents cause considerable changes in the order of affinities of the target sites and consequences in the mutagenic and carcinogenic processes can be expected.