M. flavus, M. tuberculosis [14] and B. subtilis [17]) and hyperthermophilic archaea (e.g. Nicotinamide Adenine Diphosphate; NADH plays an important role in metabolism. Nicotinamide adenine dinucleotide phosphate. Accumulating evidence has suggested that NAD (including NAD+ and NADH) and NADP (including NADP+ and NADPH) could belong to the fundamental common mediators of various biological processes, including energy metabolism, mitochondrial functions, calcium homeostasis, antioxidation/generation of oxidative stress, gene expression, immunological functions, aging, and cell … For example, shifting from homolactic to mixed-acid fermentation in Lactococcus lactis could be modulated by the decrease of NADH/NAD+ ratios under aerobic conditions [54]. It is pyridine-3-carboxylic acid, which is a component of the coenzymes NAD + and NADP +. “NADP+ phys” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia, Lakna, a graduate in Molecular Biology & Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things, What is the Difference Between NAD+ and NADP+, What are the Similarities Between NAD+ and NADP+. “Nadp.” Biology Online, 12 May 2014, Available Here, 1. A1 [21]) and single-cellular eukaryotes (e.g. Structural scheme of NAD+ and its analogs [36,73]  1,2'-fluoro ribo NAD+; 2,2'-fluoro arabino NAD+; 3, NAD+ with an inverted (arabino) configuration; BAD, benzamide adenine dinucleotide; DTA, di-(5'-thio-adenosine). In Gram-positive bacteria, the activity of NAD kinases from both Bacillus licheniformis [29] and B. subtilis [17] is inhibited intensively by NADP+; the activity of NAD kinase from M. tuberculosis is also repressed greatly by NADP+ [30], but that from both M. tuberculosis H37Rv and M. flavus is inhibited by low concentration of NADPH [14]. Further studies would not only improve our comprehension on the basic knowledge of substance metabolism, energy metabolism, metabolic regulation, and signal transduction of living organisms, but also provide new techniques in the development and application of anti-oxidative strategy, in the construction of stress resistant plants or high-producing plants, and in the development of novel anti-bacterial drugs. The molecular size of subunit from prokaryotes was approximately 30–35 kDa, e.g. However, as these one-step reactions cannot be performed circularly, they are not so effective while operated separately. The second reaction is catalyzed by pyridine nucleotide transhydrogenase that transfers a hydride from NADH to NADP+ with the concurrent production of NADPH, powered by the proton motive force [47]. Then, these reduced coenzymes can donate these electrons to some other biochemical reaction normally involved in a process that is anabolic (like the sy… This is typically done during photosynthesis in plants, or as part of sugar digestion in animals. NAD kinases from Gram-positive bacteria (e.g. Difference Between Reversible and Irreversible... What is the Difference Between ATPase and ATP... What is the Difference Between Normal Hemoglobin and... What is the Difference Between NASH and NAFLD. Three NAD kinases, NADK1, NADK2, and NADK3, were also found in Arabidopsis thaliana. But, NADP+ is reduced in the light reaction of photosynthesis and the reducing power of NADPH is used to assimilate carbon dioxide in the dark reaction. Because poly(P) is a much less expensive phosphoryl donor than ATP or any other triphosphonucleotide, Poly(P)/NTP-NAD kinase should have potential application values. It exists in nearly all classes of living organisms and is proposed to be a primitive energy source that functions as an ATP substitute. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. fluorescens(modified from Singhet al.50)  MDH, malate dehydrogenase; NADK, NAD kinase; ME, malic enzyme; PC, pyruvate carboxylase; PEPCK, phosphoenolpyruvate carboxykinase; PK, pyruvate kinase; ICL, isocitrate lyase; MS, malate synthase. Poly(P) is a polymer of inorganic orthophosphate residues linked by phosphoanhydride bonds that are energetically equivalent to that of ATP [25]. NADK1 is calmodulin (CaM) independent, and NADK2 is able to bind Ca2+/CaM, which seems to be plant specific [10,11]. Furthermore, the main function of NAD+ is to accept a hydrogen atom or in other words, a proton. Living systems have evolved numerous one-step strategies for the genesis of NADPH (Fig. Nicotinamide adenine dinucleotide. What is NAD+      – Definition, Structure, Function 2. Nicotinamide adenine dinucleotide has several essential roles in metabolism. However, the main structural difference between NADP and NAD is the presence of an additional phosphate group in the NADP on the 2′ carbon of the ribose ring, which links to the adenine moiety. Different from bacterial NAD kinases, some of the higher plant NAD kinases are regulated by CaM, thus for a long time there has been considerable interest in the regulatory effect of Ca2+/CaM on NAD kinase. Although the physiologic functions, influence pathways, and regulatory mechanisms of NAD kinases have not been clearly elucidated, some of their characteristics, functions, and potential applications have been revealed. Chloroplast NAD kinase was also essential for energy transduction through the xanthophyll cycle in photosynthesis [68]. Raffaelli et al. Involved in the regulation of the intracellular balance of NAD and NADP, and is a key enzyme in the biosynthesis of NADP. A1) could only phosphorylate NAD+, whereas NAD kinases from Gram-positive bacteria (e.g. Nicotinamide adenine dinucleotide phosphate or NADPH is a reduced coenzyme that plays a key role in the synthesis of carbohydrates in photosynthetic organisms. 1. In addition, NAD serves as a coenzyme in the reactions in the fatty acid synthesis and sterol synthesis. The role of nicotinamide adenine, or NADP, is to act as an electron carrier during the light dependent stages of photosynthesis. It creates the only obligate route for the de novo biosynthesis of NADP(H) in all living organisms. So, this is one other difference between NAD+ and NADP+. A novel anti-oxidative defense strategies for converting NADH into NADPH inP. [16]. Read "Amino acid residues that determine functional specificity of NADP‐ and NAD‐dependent isocitrate and isopropylmalate dehydrogenases, Proteins: Structure Function and Bioinformatics" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. In fact, Poly(P)/NTP-NAD kinases from mesophiles have already been used for the industrial production of NADP(H) from NAD(H) to decrease the producing cost of this diagnostic reagent [26]. NADP when it's carrying hydrogen ions. Also, both work as electron carriers. Coenzymes such as NAD (H) and NADP (H) are known for their important functions. Several lines of evidence presented here confirm the importance of IDH to respiratory processes. However, continuous supply of NADPH depends on the cyclic metabolic networks. In human cells and in rats, NAD kinase controls NADPH concentration, which in turn influences the cellular anti-oxidative defense function [56,57]. The initial purpose of the study on NAD kinase was to understand its regulatory properties, and speculate its influence on NAD(H)/NADP(H) metabolic flux. Detailed studies should be performed further to reveal the interactions of NAD kinase with NAD+ and ATP as its substrate, and with other ligands as its potential inhibitors. NADH is the reduced form of NAD+. For example, two NAD kinases, NadF and NadG, were found in Salmonella typhimurium [5]; two NAD kinases isozymes with distinctive catalytic mechanisms and Km values were presented in Euglena gracilis [6]. The function of NAD+ that is similar to that of NADP+ is that each NAD+ accepts a pair of high-energy electrons. Catalyzes specifically the phosphorylation on 2'-hydroxyl of the adenosine moiety of NAD to yield NADP. Studies on the cofactor engineering have proved that metabolic flux can be effectively regulated through controlling of key cofactors. These three NAD kinase isozymes have different functions due to particular subcellular locations, with some functions weakly rescued by their isozymes [8,9]. Together with its primary alter-egos NADH, NADP and NADPH, our private suite of pyridine-based nucleotides serve as hydride donors in some 400 … However, NADP participates in defense against oxidative stress [44], and is a substrate for the synthesis of nicotinic acid adenine dinucleotide phosphate which is a potent intracellular Ca2+-mobilizing messenger. NAD is the reduced form of NAD+. In glycolysis, glucose is converted to molecules of pyruvic acid. All these regulation can result in effective synthesis of NADPH [50] (Fig. This would be helpful for exploiting novel antimicrobial drugs. Although NAD kinase has a central role in the NAD(H)/NADP(H) metabolic network, especially in the one-step and cyclic supplying of NADPH, its regulatory mechanism has not been well elucidated. Also, both can exist in their reduced form as well, which release electrons to reduce the product, serving as a reducing agent. Whereas in microorganisms and animal cells, NAD kinase activity is not dependent on CaM, except for sea urchin eggs at the moment of fertilization and in activated human neutrophiles [61,62]. 3). Not only is NADPH vital for the generation of reactive oxygen species (ROS) (Foreman et al., 2003; Brown and Griendling, 2009; Bylund et al., 2010; Nakamura et al., 2012) and the anti-oxidative defense mechanisms of most organisms (Nordberg and Arnér, 2001; Minard and Mcalister-Henn, 2005; Singh et al., 2008), most importantly, it is also the driving force of most biosynthe… NAD is mainly used in the cellular respiration and electron transport chain whereas NADP is … Although NADP+-dependent dehydrogenases can also generate NADPH and may show positive function on anti-oxidation, they depend on a constant supply of substrate and further procession of product, hence may not be fully self-sustaining and cannot constantly supply NADPH. For example, one of the three NAD kinase isozymes of A. thaliana, NADK2, was a chloroplast NAD kinase that can bind Ca2+/CaM [10]. All these NAD+, NADH and NADPH are important co-factors in biological reactions. However, the application of NAD kinase in cofactor engineering has not been reported. Differences in catalytic properties and molecular structure also exist between microbial and human NAD kinases, such as phosphoryl donor specificity and molecular size of subunit. Recent studies have partially demonstrated that NAD kinase plays a crucial role in the regulation of NAD (H)/NADP (H) conversion. More than 200 enzymes require these coenzymes for electron transfer in redox reactions. Compounds 1 and 2 could inhibit human NAD kinase, whereas compound 3 could inhibit both the human and M. tuberculosis NAD kinase, and BAD was the most potent competitive inhibitor of the human NAD kinase [73]. E. coli [20] and Sphingomonas sp. Nicotinamide adenine dinucleotide (NAD +) is essential not only for the harvesting of energy from substrates but also for an array of regulatory reactions that determine cellular health. Both are in their oxidized state. NADPH is the typical coenzyme used in reduction reactions, seen in the anabolic pathways of organisms. CaM is a major intracellular calcium receptor in both animal and plant cells, it undergoes conformational change upon binding calcium and then interacts with a variety of target enzymes to modulate their activities [63]. NAD kinase was first discovered by Kornberg from S. cerevisiae in 1950 [13], whereas the gene encoding the NAD kinase was identified by Kawai in Micrococcus flavus and M. tuberculosis H37Rv in 2000 [14]. NAD+ refers to a coenzyme that occurs in many living cells and functions as an electron acceptor while NADP+ refers to a coenzyme that functions as a universal electron carrier, accepting electrons and hydrogen atoms to form NADPH or nicotinamide adenine dinucleotide phosphate. The growing environment and physiologic status of different organisms, as well as the consequent cellular form and level of cofactors, may also lead to the divergence of regulatory mode of NAD kinases, especially when several NAD kinase isozymes are presented. NAD and NADP act as conezymes for many degydrogenases where they are involved in transfer of hydrogen, causing either oxidation or reduction of the substrates. 5), and then measured their NAD kinase inhibitory activities. NADP+ is the used form of NADPH, and must be reduced with more electrons and a hydrogen. Significantly, the structural components of NADP are the same as NAD. A flexible loop in its active center was involved in the intersubunit contact and probably related to the NAD+ binding of the other subunit [37]. Homolog genes of NAD kinase can be found in all the sequenced genomes of living organisms, including prokaryotes and eukaryotes, with the exception of the intracellular parasite Chlamydia trachomatis [4]. Besides, both are abundant inside the cell, transferring electrons between chemical reactions. Nicotinamide Adenine Dinucleotide (NAD) and Flavin Adenine Dinucleotide(FAD) are coenzymes involved in reversible oxidation and reduction reactions. NAD acts as cofactor in redox reactions. 3). The Asp residue of GGDG motif in LmNADK1 activated the phosphor acceptor NAD+ and then made it accept the terminal phosphate residue of Mg2+–ATP to form NADP+ [36]. Traps and transfers hydrogen ions and electrons in cell reactions. Thus when cells are exposed to oxidative stress, activities of key enzymes in many metabolic pathways are regulated in order to promote conversion of pro-oxidant NADH into anti-oxidant NADPH. The regulations on PEPCK and PK could prevent pyruvate and oxaloacetate from fluxing into gluconeogenesis pathway, and enhance the acceleration of oxaloacetate which could contribute to NADH oxidation. Here, the molecular properties, physiologic functions, and potential applications of NAD kinase are discussed. NAD kinase catalyzes the phosphorylation of NAD(H) to form NADP(H), using ATP as phosphoryl donor. The three isozymes of isocitrate dehydrogenase in Saccharomyces cerevisiae differ in subunit structure, subcellular location, and cofactor specificity. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD and NADH (H for hydrogen) respectively. For the NAD kinase of hyperthermophilic archaeon Archaeoglobus fulgidus, the AMP portion of substrate ATP molecule used the same binding site as the nicotinamide ribose portion of product NADP+, i.e. Through the regulation of these ‘housekeeping’ metabolic networks, more effective anti-oxidation will be obtained by producing NADPH with concomitant expense of NADH (Fig. One nucleotide contains an adenine nucleobase and the other nicotinamide. NADP+ functions alongside many enzymes to provide energy to the many reactions in a cell. 1). Furthermore, NAD+ serves as a coenzyme in cellular respiration while NADP+ serves as a coenzyme in photosynthesis. NAD also has other functions, e.g. NAD + and NADH are converted back and forth in cellular and mitochondrial reactions that break down food into energy (i.e., ATP). Some enzymes, lysozyme or trypsin, for example, catalyze reactions by themselves, but many require helper substances such as coenzymes, metal ions, and ribonucleic acid (RNA). NAD+ is reduced to NADH in both glycolysis and TCA cycle, and the reducing power of NADH is used to generate ATP in the electron transport chain. NAD and NADP are relative coenzymes. 3). Its reduced form is NADP. Therefore, they can obtain electrons released by oxidation reactions, serving as an oxidizing agent. Therefore, NAD kinase of higher plants, especially CaM-regulated NAD kinase, may provide a novel strategy for the construction of stress resistant plants or high-producing plants. Charged or hydrophobic amino acid residues in the corresponding position gave the stringent substrate specificity of NAD+ kinases to NAD+, whereas polar amino acid or Gly residue in the corresponding position was a prerequisite for the expression of NADH kinase activity [27]. Plant NAD kinases were brought into sight earlier than those of microorganisms mainly because of the possession of both CaM-independent and CaM-regulated NAD kinase isoforms in plants. 30 kDa hexamer from E. coli [20], 32 kDa dimmer from Sphingomonas sp. NAD kinases of different organisms show sequence similarity. A1 [21], 33–35 kDa tetramer or dimer from M. tuberculosis [14,30,31], 34 kDa dimmer from M. flavus [14], and 37 kDa tetramer from archaeon P. horikoshii [19]. State Key Laboratory of Food Science and Technology. Example of a coenzyme. Methanococcus jannaschii [18] and Pyrococcus horikoshii [19]) are poly(P)/NTP-NAD kinases; NAD kinases from Gram-negative bacteria (e.g. As NAD kinase is a crucial enzyme that regulates the levels of NAD(H)/NADP(H) in the metabolic pathways, enzymatic properties of NAD kinases from several organisms have been studied in the past decade. CaM-dependent NAD kinase is essential for survival of plant under difficult conditions and for protecting plants against invading pathogens. NADPH is the reduced state of NADP. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all eukaryotes, bacteria, and archaea. NADP+/NADPH is involved in building triglycerides, cholesterol and steroid molecules, which are important in cell membranes and hormones. Recent studies have partially demonstrated that NAD kinase plays a crucial role in the regulation of NAD(H)/NADP(H) conversion. As in vitro regulatory patterns of NAD kinases differ distinctively among microbes, the control of enzymatic activity, particularly through allosteric regulation, as well as the regulatory mechanism of NAD kinase to the NAD(H)/NADP(H) metabolic flux has not been elucidated. Living organisms derive most of their energy from redox reactions, which are processes involving the transfer of electrons. The supply of NADPH in living systems can be fulfilled through several one-step enzymatic reactions (Fig. NADPH can provide electrons for reductive repairing and deoxyribose synthesis. As a crucial enzyme, the essentiality of NAD kinase has been demonstrated in several microorganisms, such as B. subtilis [2], M. tuberculosis [1], E. coli [3], S. enterica [4], Streptococcus pneumoniae [70], Staphylococcus aureus [71], Pseudomonas aeruginosa [36], and S. cerevisiae [7]. NAD kinase is a critical enzyme for the regulation of NAD(H) and NADP(H) balance (Fig. Besides the remarkable differences in substrate specificity, obvious diversities in regulatory mode also exist among NAD kinases from different sources. Identical sequences are highlighted in color shade. Furthermore, NAD+ does not contain an additional phosphate group on ribose rings while NADP+ contains a phosphate group on the 2′ carbon of the ribose ring, which carries the adenine moiety. Function od NADP. The NADK1-deficient mutant exhibited sensitivity to γ-irradiation and paraquat-induced oxidative stress, indicating that NADK1 also has an important role in protecting plants against oxidative stress [69]. Such studies showed that purified NAD kinases from some organisms were indeed regulated in vitro by effectors such as NAD(H) or NADP(H), but difference in the regulatory mode existed. The NADK2 deletion mutant displayed hypersensitivity to environmental stresses provoking oxidative stress, such as UVB, drought, heat shock, and salinity, its chlorophyll content was also reduced, indicating that NADK2 may play a vital role in chlorophyll synthesis and chloroplast protection against oxidative damage [11]. NAD+. Therefore, NAD+ kinase or NADH kinase activity is required for sustaining the NADPH level to regenerate the anti-oxidative system. This extra phosphate is added by NAD+ kin For example, the identity of E. coli NAD kinase with that of S. enterica is 96%, but with that of M. tuberculosis is 32%, and with Pos5p of S. cerevisiae is 33%. AF2372 from the hyperthermophilic archaeon Archaeoglobus fulgidus has NADP phosphatase activity in addition to fructose-1,6-bisphosphatase activity [53]. Influenced by the intracellular coenzyme levels, quick supply of NADPH is usually ensured by the cooperation of NAD kinase and NADP+-dependent dehydrogenase (e.g. However, the study by Poncet-Montange et al. Feng Shi, Yongfu Li, Ye Li, Xiaoyuan Wang, Molecular properties, functions, and potential applications of NAD kinases, Acta Biochimica et Biophysica Sinica, Volume 41, Issue 5, May 2009, Pages 352–361, https://doi.org/10.1093/abbs/gmp029. 5) indicated that di-adenosine diphosphate was a new substrate for LmNADK1, while di-(5'-thio-adenosine) (DTA) was a novel non-natural inhibitor for LmNADK1. Several lines of evidence presented here confirm the importance of IDH to respiratory processes. For example, recombinant A. thaliana NAD kinases (NADK1, NADK2, and NADK3) could not be activated by Ca2+/CaM, even though recombinant NADK2 with a Ca2+-dependent CaM-binding motif in its N-terminal was able to bind CaM [10,11]. Too much NADH can lead to the release of Fe2+ to accumulate reactive oxygen species by respiratory chain or oxidases, suggesting NADH could be a pro-oxidant [5,59]. Also, NAD+ does not contain any additional phosphate groups on ribose rings, but NADP+ contains a phosphate group on the 2′ carbon of the ribose ring, which bears the adenine moiety. Having a deficiency can cause: Deacceleration of glycolysis and Krebs’s cycle. They participate in cellular metabolism. Over 400 enzymes require the niacin coenzymes, NAD and NADP, mainly to accept or donate electrons for redox reactions (5). In general, NAD takes part in the catabolic reactions, which NADP in synthetic pathway reactions. They play a vital role in enzyme-catalyzed metabolic r… The occurrence of poly(P)-dependent NAD kinase activity in some bacteria, especially in genera of Micrococcus and Brevibacterium, was first discovered by Murata et al. In yeast Schizosaccharomyces pombe, four NAD kinase homolog genes were presented [12]. For example, when P. fluorescens was exposed to oxidative stress triggered by menadione insult, some enzymes involved in disparate metabolic modules could converge to create a metabolic network in order to convert NADH into NADPH. Both contain two nucleotides joined together via phosphate groups. Several years ago, Gerdes et al. According to the phosphoryl acceptor of NAD kinases, some studies reported that NAD kinases from Gram-negative bacteria (e.g. NAD + refers to a coenzyme that occurs in many living cells and functions as an electron acceptor while NADP + refers to a coenzyme that functions as a universal electron carrier, accepting electrons and hydrogen atoms to form NADPH or nicotinamide adenine dinucleotide phosphate. NADPH is vital in intracellular anti-oxidative defense system for most organisms, and its central role in the resistance of oxidative stress has been proved [51]. 2), all of which are responsible for substrate binding and activation. 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