Search results for “Substrate

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18 articles

Assessing Performance of Cattle Dung and Waste Cooked Foods in Producing Biogas as Single Substrate and Mixed Substrates in Kampala Uganda

Apr 2019 DOI 10.14302/issn.2377-2549.jndc-19-2701
J Mutesasira,Corresponding author External studies department, Institute of distance Education, Makerere University

Biogas is anaerobic degradation product formed from aqueous slurry of organic waste in a digester. It can be produced from cattle dung,(cd)chicken droppings, decaying leaves, kitchen waste foods(kwf), sewage sludge, slaughter house, goat, pig or sheep manure, Aqueous slurry of 200g/L of mixed or single substrate of cattle dung or/and kitchen waste evolved up to 400mL of biogas at ambient temperatures. The rate of gas evolution reached 5mL/day on the 15th day using 25% cd mixed slurry. The rates of degradation attained in the mixtures were 1.42ml/g for cd; 1.58mL/g for kwf; 1.78mL/g for 75% cd mixed substrate; 1.78mL/g for 50% cd mixed substrate; 1.92mL/g for 25% cd mixed substrate slurries. The comparative rate of biogas formation ranged from1.25 to 1.35 which was in agreement with the range published in literature of 0.8 to 5.5. Biogas can be synthesized efficiently at ambient temperature in Kampala as was done at mesophilic temperatures elsewhere. However, it may be necessary to attempt producing biogas at different pH and temperatures as well as using other substrates and inoculums.

Carbohydrates Open Access

Lignocellulosic Waste as a Sole Substrate for Production of Crude Cellulase from Bacillus subtilis PJK6 Under Solid State Fermentation Using Statistical Approach

Dec 2018
K. Bhardwaj NishiCorresponding author Joint Director, Avantha Centre for Industrial Research & Development, Paper Mill Campus, Yamuna Nagar – 135 001 (Haryana)

The agricultural organic wastes pose major environmental issues and their inappropriate disposal is a major cause of pollution while these as cheap lignocellulosic resources can be utilized for many value added products such as enzymes. The purpose of the present study was to utilize wheat bran as a sole substrate for enhanced cellulase production under submerged fermentation (SMF) or solid state fermentation (SSF) and optimize the various process variables involved in the selected fermentation type. In order to achieve high titer of cellulase, a central composite design (CCD) was constructed and performed for optimization of SSF with five process variables at five coded levels. A 25 full factorial design was constructed leading to a set of 50 experiments that were performed in triplicates. The key variables namely incubation time, temperature, wheat bran and tap water ratio, pH and inoculum size were evaluated. The optimization of the process variables resulted in 1.14 IU/ml of cellulase activity from Bacillus subtilis PJK6 under SSF using wheat bran as a sole organic substrate with tap water. The optimum conditions included incubation time- 72 h, temperature- 45oC, pH- 6, inoculum size- 14% with 1:4 as wheat bran and tap water ratio. The production of cellulase using only moistened wheat bran was demonstrated and found to be significantly controlled by incubation time and temperature while pH showed the least effect. The economic production of valuable and useful enzyme using agricultural residue was achieved at moderate conditions from a GRAS microbe that can benefit the industry as well as the environment.

Substrate Stiffness Influences the Time Dependence of CTGF Protein Expression in Müller Cells

Jan 2018 DOI 10.14302/issn.2578-8590.ipj-17-1910
J Foster WilliamCorresponding author Department of Physics, University of Houston, Houston, TX, USA

Following ocular trauma and retinal detachment, gliotic changes in the retina may develop over the subsequent month, a process known as PVR (proliferative vitreoretinopathy). There have been no successful therapeutic interventions to inhibit PVR. The protein CTGF (Connective Tissue Growth Factor) has been associated with retinal PVR and other fibrotic diseases of the retina in clinical studies but the mechanistic link between different pathologies and retinal gliosis has not been determined. In addition, CTGF has been previously noted to be associated, in some cases, with YAP/TAZ (Yes-associated protein and Tafazzin protein complex), transcriptional regulatory proteins that change subcellular localization in response to mechanical cues, such as the stiffness of the underlying material. We have previously shown that the mRNA for CTGF is markedly (100-fold) upregulated in retinal Müller cells grown on soft substrates. In order to evaluate if the mechanism by which mechanotransduction modulating CTGF production in retinal Müller cells involves the YAP/TAZ complex, this study tests the influence of substrate stiffness on the time dependence of CTGF protein expression, as well as subcellular localization of YAP/TAZ using a conditionally-immortalized mouse retinal Müller cell line plated on laminin-coated, polyacrylamide substrates of varying elastic modulus. Changes were assayed using immunohistochemistry and ELISA (Enzyme-Linked ImmunoSorbent Assay). In retinal Müller cells, the relationship between elastic modulus and the pattern of CTGF protein expression was bimodal, with CTGF levels rising more rapidly for cells on hard substrates and more slowly for cells grown on soft substrates. In addition, nuclear localization of YAP/TAZ corresponded directly to the maximum CTGF expression.

Benzoate Concentration and Cooperativity by a Substrate for Benzoate 1,2-dioxygenase from Benzoate-Degrading Rhodococcus Opacus 1CP

Dec 2017 DOI 10.14302/issn.2576-6694.jbbs-17-1860
P. Solyanikova InnaCorresponding author Laboratory of enzymatic degradation of organic compounds, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russia.

We explored the effect of a change in substrate-benzoate (as sole carbon and energy source) concentration in growth medium on the activity of benzoate 1,2-dioxygenase (BDO) of R.opacus 1CP cells, where BDO is the enzyme mediated the initial attack of benzoate. The activity of the enzyme was estimated by a change of respiration of whole freshly harvested bacterial cells (growth of the cells on benzoate) in response to injection of benzoate. It was shown that when concentration of growth substrate-benzoate decreased from 6 g/L to 250 mg/L, the curves of the dependency of the response rate to benzoate on the initial concentration of benzoate demonstrated that kinetics of the process changes from hyperbolic saturation kinetics, or typical Michaelis-Menten kinetics, to sigmoidal dependency of V on S. The semisaturation constant as a characteristic of the strength of substrate binding with BDO changed simultaneously. These changes were accompanied by the increase in the Hill coefficient from 1.02 up to 3.06, hence positive kinetic cooperativity by a substrate was observed for BDO of R.opacus 1CP cells. The influence of this type of cooperativity on viability of rhodococcus in natural environment and causes of the changes mentioned are discussed. It was hypothesized that an increase in substrate concentration in the medium for the growth of the bacterium not only stimulated synthesis of the inducible enzyme (BDO) in the cell but also led to the change in BDO conformation followed by the change in interaction between substrate-binding active sites of enzymes.

Correlation of Oncotype DX Recurrence Score with the Expression of Insulin Receptor Substrate Proteins in Estrogen Receptor + Breast Cancer

May 2014 DOI 10.14302/issn.2572-3030.jcgb-13-369
Khan AshrafCorresponding author Departments of Pathology, UMass Memorial Medical Center, University of Massachusetts Medical School, Worcester, MA 01605, USA

Insulin receptor substrate (IRS) 1 and 2 are downstream signaling proteins that influence breast pathophysiology. IRS-1 promotes carcinoma cell proliferation; whereas IRS-2 regulates cell motility, invasion, and glycolysis. Our lab has shown that distinct cellular localization of IRS-2 also plays a role in carcinoma cell function. Oncotype DX (Genomic Health) (ODX) is a 21-gene expression profile used to classify carcinomas with low, intermediate, and high risk recurrence scores (RS). Our aim is to correlate expression and cellular localization of IRS proteins in breast carcinomas with their ODX RS. 97 breast carcinomas sent for ODX testing from 2006-2009 were collected and grouped according to their RS (low, intermediate or high). Immunohistochemistry for IRS-1/-2 was performed. Specific criteria were used to evaluate IRS staining patterns. Follow-up data, ranging from 3-6 years, was available. Statistical analysis was performed to correlate staining patterns of IRS-1/-2 with the three RS groups. IRS-1 staining, predominantly nuclear, did not significantly correlate with RS (P=.5645). IRS-2 expression patterns did show statistical significance amongst the three RS groups (P=.0371). Tumors with intermediate and low RS were more likely to exhibit punctate and diffuse cytoplasmic expression of IRS-2, and cell membrane expression was uncommon in this group. Expression and cellular localization of IRS proteins play an important role in breast cancer cell biology, and expression patterns for IRS-2 do demonstrate a significant correlation with ODX RS. Further studies are required to elucidate the significance of cellular localization of IRS-1/-2 proteins in breast carcinoma cells and their relationship to ODX scores.

Fungal Diversity Open Access

Keratinophilic Fungi: Diversity And Abundance in the Soil of Ajmer District, Rajasthan

Jul 2025 DOI 10.14302/issn.2766-869X.jfd-25-3841
Jangid RenuCorresponding author

Soil is a natural habitat and ecosystem for microorganisms, including bacteria and fungi. Mostly keratinophilic fungi are found in soil, use keratin as a growth substrate, and are essential to the natural degradation of keratin waste. These fungi include dermatophytes, a potential source of infectious diseases in humans and animals and cause dermatophytosis. One hundred thirty-six soil samples were collected from several sites including animal habitats in Ajmer district, Rajasthan, India. The soil samples were used for the study of keratinophilic fungi related to species richness, abundance, and diversity. The Physio-chemical properties of collected soil samples were analyzed and examined in soil microflora for temperature, pH, and macronutrients including nitrogen, phosphorus, and potassium. Ninety-eight soil samples (72%) showed positive results for the keratinophilic fungal isolates. The isolated fungal species belonging to eight genera and seventeen species included Aspergillus niger, A. flavus, A. fumigatus, Chrysosporium tropicum, Microsporum gypseum, M. canis, Fusarium solani, F. oxysporum, F. verticilloides, Trichophyton mentagrophytes, T. rubrum, T. tonsurans, T. terrestre, T. equinum, Penicillium, Mucor circinelloides, and Blastomyces. The temperature recorded for keratinophilic fungi ranged between 25℃ and 37℃ and pH was found in the range of 7.0 to 8.5. The fungal community was dominated by the order Onygenales followed by Eurotiales and Hypocreales belonging to the phylum Ascomycota.

Adopting a Wider Approach for Fisheries Management

May 2022 DOI 10.14302/issn.2643-0282.imsj-22-4160
Donald Hawkins AnthonyCorresponding author Kincraig, Blairs, Aberdeen, Scotland, United Kingdom.

Many marine and freshwater fisheries are now in a very poor state, and many fish stocks are close to collapse. There is a need to manage fisheries more carefully, especially since fishing can affect other aspects of the environment. It is also important to reduce the adverse effects of climate changes upon the marine and freshwater environments, fishes, and other animals, and the need to manage other human activities taking place in the sea, to improve the marine environment and protect the wildlife and the fishing activities. Marine pollution, includes human waste materials, chemicals and plastics, and there is also noise and substrate vibration, from industrial and other activities that may affect both the abundance and quality of fishes and other marine animals. This paper deals with fisheries management, and environmental protection, and concludes that fishermen, fisheries scientists, fisheries managers and environmental interests must work closely together, if fishes are to be adequately protected, and fisheries are to be better managed. It describes current systems of management. It especially draws attention to the importance of moving towards an ecosystem-based approach to fisheries management. Such an approach aims to manage all those human activities that have an impact upon the marine environment and its life forms.

Thin Film Deposition and Characterization Techniques

Apr 2022 DOI 10.14302/issn.2831-8846.j3dpa-22-4066
Geremew TemesgenCorresponding author Debark University, Department of physics, Debark, Ethiopia

Thin films are everywhere in the modern world, with many of the technologies we depend upon in daily life being, in turn, dependent upon thin film technology. Chemical bath deposition includes principles of chemical bath deposition (CBD) and concept of solubility product, nucleation and film growth, thin film deposition mechanism in chemical bath deposition. The non-metallic ion source (anions) and metal ion source (cations) then react to form the compound. The nucleation process plays an important role in determining the crystallinity and microstructure of the resultant film. From the discussion of deposition techniques which are physical and chemical deposition methods. Physical deposition techniques contains sputtering deposition, electron beam evaporation and physical vapour deposition (PVD) process have been known for over 100 years and also fabrication films on the substrate, as well as the increasement of the pressure in the chamber due to operation of the sources indicates directly that gases or vapors are desorbed. Chemical deposition process is economically effective and has been industrially exploited to large scale. It can be summarized that thin film characterization techniques include X-ray diffraction (XRD), UV-Vis spectrophotometer, scanning electron microscopy, energy dispersive x-ray diffraction, transmission electron microscopy (TEM). X-rays diffraction (XRD) is a rapid and a powerful technique used to study the phase of a crystalline material, information on unit cell lattice parameters, crystal structure, crystal orientation and crystalline size.

A Review on Lab Scale Cultivation of Calocybe Indica and Its Medicinal Value

Dec 2020 DOI 10.14302/issn.2379-7835.ijn-20-3406
Petchimuthu PriyaCorresponding author Kalasalingam Academy of Research and Education, Krishnankoil

Calocybe indica, a tropical edible mushroom and it is popular because it has good nutritive value and it can be cultivated commercially on a large scale. Mushrooms are in the great demand everywhere and hold a unique place in the world today due to their typical taste and rich in protein, vitamins, minerals. Other than nutritional value, it is also playing a major role in medicinal field. Milky mushroom is known to have anti-oxidant and anti-cancer effect. Paddy in particular used as a substrate in Milky mushroom considered as inexpensive and it is a popular variety among people because of its distinct flavor, higher protein content and shorter cropping duration compared to other cultivated mushrooms. The present study designed to explain how the mushroom was cultivated using paddy straw in India.

Optimization, Production, Purification of Laccase Enzyme from Bacillus sp

Jul 2020 DOI 10.14302/issn.2377-2549.jndc-20-3460
Tamilvanan NivedharshiniCorresponding author India

Laccase enzyme production is important and more beneficial for environment, because it has many roles like, involved in bioremediation, biodegradation, decolorization of environmental polluted dyes and pharmaceutical sector also. Production of laacse enzyme from bacillus sp as using of Agro waste (rice bran) as a substrate. The Agricultural soil sample was collected, after the sample were processed for the preliminary and biochemical tests to identification of Bacillus organism. The Guiacol inducer were used for microbial screening of laccase enzyme production. After that microbial screening, various optimization parameters (pH, Temperature, Inducers, carbon and nitrogen sources) are checked for that production of laccase enzyme in mass level. Based on that optimization the bulk fermentation (large scale) (solid state fermentation) were done as a rice bran substrate. The fermentation product was subjected to analyzed the physiochemical properties and purification based on that techniques of Gel filtration chromatography, Dialysis, Ammonium sulfate preciptation. The protein estimation of that product to analysed by lowry’s method.

Agronomy Research Open Access

Arbuscular Mycorrhizal Biofertilizers Sources in the Potato (Solanum Tuberosum) Plant show Interactions with Cultivars on Yield and Litter-bags Spectral Features

Feb 2020 DOI 10.14302/issn.2639-3166.jar-20-3185
Masoero GiorgioCorresponding author Accademia di Agricoltura di Torino, Via A. Doria 10, 10123 Torino (Italy).

Four strains of Arbuscular Mycorrhizal (AM) biofertilizer fungi, combined with two potato cultivars, were in-field tested in a four-replicate arrangement in a factorial experiment. As far as general combinability is concerned, cv. Agria was more responsive to different inocula (yield +5.56%, P 0.02) and to  two strains in particular (+8%). On the other hand, the results with Innovator, a cultivar that yields 33% less than Agria, showed a significant reduction in the number of tubers for three AM strains, thus proving a clear genetic Biofertilizer * Cultivar interaction. The study of hay litter-bags has shown a high NIR spectral fingerprint for the Cultivar factor (81%), while the Inoculation factor showed a higher spectral fingerprint in Agria (76%) than in Innovator (65%). The Substrate Induced Respiration predicted from the NIR-SCiO spectra of the litter-bags was significantly increased after inoculation (+6.3%, P 0.04), but appeared lower for Agria (-5.4%) vs. Innovator (P 0.05), with a non-significant interaction. The obtained results show that the adaptation of the AM strains to the genetics of potato cultivars  is a first step toward reducing chemical inputs, with consequent benefits for the environment, but without an excessive reduction in yield. The litter-bag technique can therefore be recommended for a simplified monitoring of the complicated plant-mycorrhizosphere relationship. 

Peroxidase from Coleus Forskohlii: Purification and Biochemical Characterization

Jan 2020 DOI 10.14302/issn.2379-7835.ijn-19-3139
Q. Almulaiky YaaserCorresponding author Chemistry Department, Faculty of Sciences and Arts, University of Jeddah, Khulais, P.O. Box 355, Khulais, 21921, Saudi Arabia

In this study, a peroxidase from new source was purified using ion exchange and gel filtration techniques. The recovery for peroxidase activity was 19% with 11-fold purification and specific activity of 749 unit/mg protein. Purified peroxidase demonstrated a molecular mass of 39 kDa using gel filtration and was confirmed as a single band on SDS-PAGE. The purified peroxidase revealed a broad optimum pH activity at 6.0-6.5 and 50°C temperature. The kinetic parameters for purified peroxidase toward H2O2 and guaiacol as substrates were found to be Km = 3.355, 5.395 mM, Kcat = 99.52, 79.56 s-1 and Vmax =1.531, 1.242 µmole ml-1 min-1, respectively. The catalytic efficiency (kcat/Km) of the purified peroxidase was 14.75 and 29.66 s−1 mM−1 for guaiacol and H2O2, respectively. Peroxidase activity was observed to be enhanced by Cu2+, Co2+, Ni2+ and inhibited in the presence of Sn2+, Al3+, Hg2+, NaN3, EDTA and urea. Characterization showed that peroxidase purified from C. forskohlii has the ability to be used for food industrial applications.

Enzymes Open Access

Trichoderma reesei (Hypocrea jecorina) Bgl1 is a Novel, Exo-Acting Glucanase and Xylanase

Dec 2019 DOI 10.14302/issn.2690-4829.jen-19-3105
Brumm PhillipCorresponding author C5-6 Technologies LLC, 5627 Old Oak Drive, Fitchburg, WI 53711, USA

Trichoderma reeseiβ-glucosidase (Bgl1) is one of four enzymes demonstrated to act synergistically to degrade cellulose both in vitro and in vivo. Our work attempted to better understand the substrate specificity and potential biotechnological applications of Bgl1. T. reesei Bgl1H cleaves over 80% of the β-(1-4) and β-(1-3) linkages in β-glucan and 14% of the β-(1-4) linkages in amorphous cellulose, significantly more than any tested bacterial β-glucosidase. Bgl1H cleaves 50% of the β-(1-4) linkages in xyloglucan when supplemented with cellulase and α-xyloside. Approximately 20% conversion to glucose was obtained from insoluble β-(1,3)-linked curdlan using only Bgl1H; addition of a curdlanase resulted in conversion of approximately 70% of the curdlan to glucose. Bgl1H also produces xylose from xylooligosaccharides and debranched xylans. For both glucans and xylans, the relative rates of hydrolysis increase with increasing polysaccharide chain lengths. Bgl1H is able to partially degrade β-glucan in a variety of grain components; addition of endo-acting enzymes improved the enzyme’s performance on these grain components. The ability of this enzyme to produce monosaccharides from undigestible polysaccharides suggest it may have potential in improving utilization of carbohydrates in animal feed, fermentations, and other biotechnological applications.

Graphical Approach to Compare Concentration Constants of Hill and Michaelis-Menten Equations

Sep 2018 DOI 10.14302/issn.2576-6694.jbbs-18-2280
V. Emelyanova ElenaCorresponding author FSBIS G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Science, Pushchino, Moscow Region, Russia.

The aim of present study was to describe the graphical technique how to go from Hill concentration constant to Michaelis constant. To compare enzymatic processes, the kinetics of which is subjected to different regularities, it is possible to use constants that characterize catalytic activity (Vmax) and concentration constants that are the substrate concentration at which the rate of the enzymatic process is equal to a half of maximum permissible rate. Concentration constants are S0.5 for Hill equation and Km for Michaelis-Menton equation. The graphical approach was proposed in order to go from concentration constant of Hill equation to Michaelis concentration of the process that could be characterized by the same catalytic activity (the same values of minimum and maximum rates) similar to that observed in the process described by Hill equation.

Polysaccharide Transglycosylases: A Survey of Assay Methods

May 2018 DOI 10.14302/issn.2832-5311.jpcd-18-2077
Farkaš VladimírCorresponding author Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, 84538 Bratislava, Slovakia

Polysaccharide transglycosylases (PTGs) are a unique group of glycoside hydrolases playing important roles in the formation and modification of plant and fungal cell walls. Their action involves cutting the molecule of the polysaccharide substrate at the glycosidic bond, followed by transfer of the newly formed reducing-end fragment to the non-reducing end of another polysaccharide molecule, with the formation of a new glycosidic bond. As there is no net increase in the number of reducing ends in the system, conventional reductometric methods used to assess the activity of glycoside hydrolases are ineffective. Since the PTGs participate in vital processes, such as the elaboration of cell walls in plants and fungi, and are not present in animal cells, they are considered as possible targets for future specific fungicides and herbicides. Biochemical studies of PTGs, as well as the search for their inhibitors, require the availability of convenient and efficient methods for their assay. In this review we briefly describe the principles of methods used to detect and to determine the activity of this important group of enzymes.

Enzymes Open Access

Hydrolysis of Cellulose by Soluble Clostridium Thermocellum and Acidothermus Cellulolyticus Cellulases

Apr 2018 DOI 10.14302/issn.2690-4829.jen-18-2025
Brumm PhillipCorresponding author C5-6 Technologies LLC, 5627 Old Oak Drive, Fitchburg, WI 53711, USA

The goal of this work was to clone, express, characterize and assemble a set of soluble thermostablecellulases capable of significantly degrading cellulose. We successfully cloned, expressed, and purified eleven Clostridium thermocellum (Cthe) cellulases and eight Acidothermuscellulolyticus(Acel) cellulases. The performance of the nineteen enzymes was evaluated on crystalline (filter paper) and amorphous (PASC) cellulose. Hydrolysis products generated from these two substrates were converted to glucose using beta-glucosidase and the glucose formed was determined enzymatically. Ten of the eleven Cthe enzymes were highly active on amorphous cellulose. The individual enzymes all produced <10% reducing sugar equivalents from filter paper. Combinations of Cthe cellulases gave higher conversions, with the combination of CelE, CelI, CelG, and CelK converting 34% of the crystalline cellulose. All eight Acel cellulases showed endo-cellulase activity and were highly active on PASC. Only Acel_0615 produced more than 10% reducing sugar equivalents from filter paper, and a combination of six Acel cellulases produced 32% conversion. Acel_0617, a GH48 exo-cellulase, and Acel_0619, a GH12 endo-cellulase, synergistically stimulated cellulose degradation by the combination of Cthe cellulases to almost 80%. Addition of both Acel enzymes to the Cthe enzyme mix did not further stimulate hydrolysis. Cthe CelG and CelI stimulated cellulose degradation by the combination of Acel cellulases to 66%.

Isolation and Screening of Phb Producing Halotolerant Bacterial Strains from A Saline Environment

Nov 2017 DOI 10.14302/issn.2576-6694.jbbs-17-1783
Krishnaswamy VeenaGayathriCorresponding author Department of Biotechnology, Stella Maris College, Chennai-86, Tamilnadu, India

Plastic materials have been used as packaging materials and also have other numerous applications because of their durability and stability. Plastic products are non degradable and they continue to exist in the environment thereby causing a serious threat to the ecosystem. Bioplastics which are biodegradable plastics are emerging out as a boon to overcome the problem of plastic accumulation. Polyhydroxybutyrate or PHB is a bioplastic that serves as an alternative to synthetic plastics. PHB is a lipid reserve material that gets accumulated within the cell wall of micro organisms under stress conditions. Halophilic microorganisms can be of much use in the production of PHB as it is cost – effective and recovery of PHB is much easier in halotolerant organisms. Hence this study focuses on the isolation of PHB producing halotolerant bacterial organisms from marine sources. Screening of PHB positive isolates was done by Sudan Black B and Nile blue A staining. Large scale production of PHB by the efficient bacterial strain was done by using wastewater as the substrate.

Kynurenines and Vitamin B6: Link Between Diabetes and Depression.

Sep 2013 DOI 10.14302/issn.2374-9431.jbd-13-218
Oxenkrug GregoryCorresponding author Psychiatry and Inflammation Program, Department of Psychiatry, Tufts University School of Medicine and Tufts Medical Center, Boston MA, USA.

The increased association between depression and diabetes mellitus is generally acknowledged. Recent studies suggest that depression leads to diabetes.However, the underlying molecular mechanisms for this association remain unclear.Literature and our data indicate that inflammatory and/or stress factors in depression up-regulate tryptophan (TRP) conversion into kynurenine (KYN), a substrate for nicotinamide adenine dinucleotide (NAD) biosynthesis. Deficiency of vitamin B6, a co-factor of the key enzymes of KYN – NAD pathway, shunts KYN metabolism from formation of NAD towards production of xanthurenic (XA) and kynurenic (KYNA) acids. Human and experimental studies reveal that XA, KYNA and their metabolites interfere with production, release and biological activity of insulin. We propose that inflammation- and/or stress-induced up-regulation of TRP – KYN metabolism in combination with vitamin B6 deficiency is one of the mechanisms mediating increased risk of diabetes in depression. Consequently, monitoring formation of diabetogenic KYN derivatives might help to identify subjects-at-risk for the development of diabetes. Pharmacological down-regulation of the TRP – KYN – NAD pathway and maintenance of adequate vitamin B6 status might help to prevent the development of diabetes in depression and other conditions associated with inflammation/stress–induced excessive production of KYN and vitamin B6 deficiency, e.g., obesity, cardiovascular diseases, aging, menopause, pregnancy, and hepatitis C virus infection.

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