To improve communications between enzymes and electrodes, many different methods were developed including the use of diffusional electron mediators, the “wiring” of enzymes through immobilization in redox polymers, the functionalization of enzymes with electron relays, and the use of nanomaterials. Recently a new promising strategy was reported, in which the glycoprotein glucose oxidase (GOx) was directly electrically contacted with the electrodes after removal of the glycosylating layer. Although a lot of advances in the electrical communication between enzymes and electrodes has made it possible to fabricate new biosensors and biofuel cells, the technologies still face challenging issues, such as development of long-term stable miniaturized implantable amperometric biosensors and biofuel cells. Our approach to the development of a glucose biofuel cell anode is based on the combination of different redox enzymes with complementary oxidation positions thus forming a reaction cascade to oxidize the substrate at more than one position. Improvements in current density and coulombic efficiency of a glucose oxidizing electrode were realized by a combination of pyranose dehydrogenase from Agaricus meleagris ( Am PDH) with either glucose dehydrogenase from Glomerella cingulata ( Gc GDH) or cellobiose dehydrogenase from Myriococcum thermophilum ( Mt CDH). The mixed enzyme electrode oxidizes glucose in several combinations at the C-1, C-2 and C-3 positions of the pyranose ring. This concerted action of enzymes increases (i) the coulombic efficiency by extracting more than 2 e - per substrate molecule and (ii) the current density of the electrode when the mass-transfer of substrates becomes rate limiting. The electrodes were investigated with flow injection analysis (FIA) using different substrates under physiological conditions (pH 7.4). These investigations showed that the product of one enzyme can be used as substrate for the other enzyme and maximally 6 e - can be gained from the oxidation of one glucose molecule using mixed enzyme electrodes like Am PDHb/ Gc GDH/Os-polymer 2 or the Am PDHa/ Mt CDH/Os-polymer 1. We propose a bioanode for use in biofuel cells with an increased current density and coulombic efficiency obtained by a cascade reaction catalyzed by redox enzymes with a different site-specificity for glucose. Key words: Bio-anode, glucose dehydrogenase, Os-polymers, pyranose dehydrogenase, cellobiose dehydrogenase, coulombic efficiency
A new extracellular flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase from Glomerella cingulata ( Gc GDH) was electrochemically studied as a recognition element in glucose biosensors. The redox enzyme was recombinantly produced in Pichia pastoris , homogeneously purified and its glucose oxidizing properties on spectrographic graphite electrodes were investigated. Six different Os-polymers, the redox potentials of which ranging in a broad potential window between +15 and +489 mV vs. NHE, were used to immobilize and “wire” Gc GDH to the spectrographic graphite electrode’s surface. The Gc GDH/Os-polymer modified electrodes were evaluated by chronoamperometry using flow injection analysis. The current response was investigated using a step-wisely increased applied potential. It was observed that the ratio of Gc GDH:Os-polymer and the overall loading of the enzyme electrode significantly affect the performance of the enzyme electrode for glucose oxidation. The best suited Os-polymer [Os(4,4¢-dimethyl-2,2¢-bipyridine) 2 (PVI)Cl] + had a potential of +309 mV vs. NHE and the optimum Gc GDH:Os-polymer ratio was 1:2 yielding a maximum current density of 493 µAcm -2 at a 30 mM glucose concentration. Key words: Glucose dehydrogenase, FAD, Os-polymers, glucose biosensor, chronoamperometry, oxygen reactivity.
Today hypertension has become a threat to the human lives. Different factors like sensitivity to sodium, obesity, alcohol consumption, sedentary lifestyle and smoking are responsible for the development of hypertension. Hypertension can be of major risk factor to cardiovascular diseases (CVD). Because of their small molecular mass, bioactive peptides have an important role in the digestion and absorption of proteins. Angiotensin converting enzyme inhibitory (ACE-I) peptides are one of the most widely used bioactive peptide in the field of medicine and food processing. Thus, these inhibitors are applied to regulate the blood pressure and prevent hypertension. Synthetic ACE inhibitors have various side effects and that is why scientists nowadays, are focusing on the natural alternate of ACE inhibitors with promising health properties. Two types of proteins found in milk are casein and whey proteins which are a good source of the bioactive peptides having a positive impact on body functions. ACE inhibitory peptides derived from the goat milk proteins are considered to be used in nutraceuticals and pharmaceutical products to reduce the hypertension ultimately reducing the risk of CVD and other related diseases.
The gut microbiota has the capacity to de-novo manufacture or change endogenous and exogenous substances to produce or alter xenometabolites (i.e., non-host-derived metabolites). A wide-scale characterization of these metabolites is still lacking, despite rare instances of xenometabolites impacting host health and illness. Numerous studies have been conducted to investigate how the gut microbiome affects individual function and health, including links between specific intestinal microorganism populations and metabolites and the health of the systemic-immune system and gastrointestinal tract. The current review article delves into the sources of xenometabolites and the role of modeling in addressing the complexity of the xenometabolites process, as well as various nutraceutical benefits such as antibiotics, anti-tumor, and anti-cancer action.
The world population is incessantly increasing, and humans are bound to depend on limited land resources. In order to survive, it's imperative to derive maximum from limited available resources while minimizing the human impacts to the least. Soil security is one of the promising means to ensure food, fiber, bioenergy, and water quality that can be achieved by precluding it from major threats, i.e., urbanization, organic matter loss, and soil degradation. Soil is an essential resource being degraded rapidly by swiftly changing global trends in human lifestyles, enhanced competition for limited resources, large-scale migration trends, climate change, and high demand for energy. Rapid globalization fetches increased pressure on agricultural soils. High demand for food, fiber, and bioenergy deprives soils of their nutrition and organic matter. Greater utilization of fertilizer and pesticides is concomitant with high cost and problems like water pollution yielding insufficient food to fulfill the global demands of the incessant population. This chapter demonstrates the importance of soil security and its role in the mitigation of global food, water, and energy crisis. Besides, it outlines major threats to soils along with global shifting trends as a big hurdle in a way of attaining sustainable development goals. We will conclude by discussing potential land management strategies to secure and restore soils in order to get maximum benefits in a sustainable manner.
A new extracellular flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase from Glomerella cingulata ( Gc GDH) was electrochemically studied as a recognition element in glucose biosensors. The redox enzyme was recombinantly produced in Pichia pastoris , homogeneously purified and its glucose oxidizing properties on spectrographic graphite electrodes were investigated. Six different Os-polymers, the redox potentials of which ranging in a broad potential window between +15 and +489 mV vs. NHE, were used to immobilize and “wire” Gc GDH to the spectrographic graphite electrode’s surface. The Gc GDH/Os-polymer modified electrodes were evaluated by chronoamperometry using flow injection analysis. The current response was investigated using a step-wisely increased applied potential. It was observed that the ratio of Gc GDH:Os-polymer and the overall loading of the enzyme electrode significantly affect the performance of the enzyme electrode for glucose oxidation. The best suited Os-polymer [Os(4,4¢-dimethyl-2,2¢-bipyridine) 2 (PVI)Cl] + had a potential of +309 mV vs. NHE and the optimum Gc GDH:Os-polymer ratio was 1:2 yielding a maximum current density of 493 µAcm -2 at a 30 mM glucose concentration. Key words: Glucose dehydrogenase, FAD, Os-polymers, glucose biosensor, chronoamperometry, oxygen reactivity.
To improve communications between enzymes and electrodes, many different methods were developed including the use of diffusional electron mediators, the “wiring” of enzymes through immobilization in redox polymers, the functionalization of enzymes with electron relays, and the use of nanomaterials. Recently a new promising strategy was reported, in which the glycoprotein glucose oxidase (GOx) was directly electrically contacted with the electrodes after removal of the glycosylating layer. Although a lot of advances in the electrical communication between enzymes and electrodes has made it possible to fabricate new biosensors and biofuel cells, the technologies still face challenging issues, such as development of long-term stable miniaturized implantable amperometric biosensors and biofuel cells. Our approach to the development of a glucose biofuel cell anode is based on the combination of different redox enzymes with complementary oxidation positions thus forming a reaction cascade to oxidize the substrate at more than one position. Improvements in current density and coulombic efficiency of a glucose oxidizing electrode were realized by a combination of pyranose dehydrogenase from Agaricus meleagris ( Am PDH) with either glucose dehydrogenase from Glomerella cingulata ( Gc GDH) or cellobiose dehydrogenase from Myriococcum thermophilum ( Mt CDH). The mixed enzyme electrode oxidizes glucose in several combinations at the C-1, C-2 and C-3 positions of the pyranose ring. This concerted action of enzymes increases (i) the coulombic efficiency by extracting more than 2 e - per substrate molecule and (ii) the current density of the electrode when the mass-transfer of substrates becomes rate limiting. The electrodes were investigated with flow injection analysis (FIA) using different substrates under physiological conditions (pH 7.4). These investigations showed that the product of one enzyme can be used as substrate for the other enzyme and maximally 6 e - can be gained from the oxidation of one glucose molecule using mixed enzyme electrodes like Am PDHb/ Gc GDH/Os-polymer 2 or the Am PDHa/ Mt CDH/Os-polymer 1. We propose a bioanode for use in biofuel cells with an increased current density and coulombic efficiency obtained by a cascade reaction catalyzed by redox enzymes with a different site-specificity for glucose.
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