1
|
Ribeiro JM, Costas MJ, Cabezas A, Meunier B, Onoufriadis A, Cameselle JC. The TKFC Ala185Thr variant, reported as "null" for fructose metabolism, is fully active as triokinase. FEBS Lett 2022; 596:1453-1457. [PMID: 35114011 DOI: 10.1002/1873-3468.14309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/30/2022] [Indexed: 11/11/2022]
Abstract
TKFC-encoded triokinase catalyzes glyceraldehyde phosphorylation in fructose metabolism and favors lipogenesis in mice. In Tkfc knockouts or knockdowns, fructose oxidation predominates over lipogenesis. The highly-prevalent human variant Ala185Thr-TKFC has been reported to be "null" for fructose metabolism, since Ala185-TKFC rescues the mouse TKFC-deficient phenotype, whereas Ala185Thr-TKFC does not. Such report implies that most humans would display a non-canonical fructose metabolism, but it ignores the well-characterized triokinase activity of Ala185Thr-TKFC. Here, earlier evidence is summarized, along with new evidence that both human variants are equally active in yeast. Therefore, future research on triokinase in the context of human fructose metabolism should consider that Ala185Thr-TKFC is not biochemically "null".
Collapse
Affiliation(s)
- João M Ribeiro
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina y Ciencias de la Salud, Universidad de Extremadura, Badajoz, Spain
| | - María Jesús Costas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina y Ciencias de la Salud, Universidad de Extremadura, Badajoz, Spain
| | - Alicia Cabezas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina y Ciencias de la Salud, Universidad de Extremadura, Badajoz, Spain
| | - Brigitte Meunier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Alexandros Onoufriadis
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, UK
| | - José Carlos Cameselle
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina y Ciencias de la Salud, Universidad de Extremadura, Badajoz, Spain
| |
Collapse
|
2
|
Onoufriadis A, Cabezas A, Ng JCF, Canales J, Costas MJ, Ribeiro JM, Rodrigues JR, McAleer MA, Castelo-Soccio L, Simpson MA, Fraternali F, Irvine AD, Cameselle JC, McGrath JA. Autosomal recessive hypotrichosis with loose anagen hairs associated with TKFC mutations. Br J Dermatol 2020; 184:935-943. [PMID: 32790068 DOI: 10.1111/bjd.19481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Loose anagen hair is a rare form of impaired hair anchorage in which anagen hairs that lack inner and outer root sheaths can be gently and painlessly plucked from the scalp. This condition usually occurs in children and is often self-limiting. A genetic basis for the disorder has been suggested but not proven. A better understanding the aetiology of loose anagen hair may improve prevention and treatment strategies. OBJECTIVES To identify a possible genetic basis of loose anagen hair using next-generation DNA sequencing and functional analysis of variants identified. METHODS In this case study, whole-exome sequencing analysis of a pedigree with one affected individual with features of loose anagen hair was performed. RESULTS The patient was found to be compound heterozygous for two single-nucleotide substitutions in TKFC resulting in the following missense mutations: c.574G> C (p.Gly192Arg) and c.682C> T (p.Arg228Trp). Structural analysis of human TKFC showed that both mutations are located near the active site cavity. Kinetic assays of recombinant proteins bearing either of these amino acid substitutions showed almost no dihydroxyacetone kinase or D-glyceraldehyde kinase activity, and FMN cyclase activity reduced to just 10% of wildtype catalytic activity. CONCLUSIONS TKFC missense mutations may predispose to the development of loose anagen hairs. Identification of this new biochemical pathobiology expands the metabolic and genetic basis of hypotrichosis.
Collapse
Affiliation(s)
- A Onoufriadis
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, Guy's Hospital, King's College London, London, UK
| | - A Cabezas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - J C F Ng
- Randall Centre for Cell and Molecular Biophysics, Guy's Hospital, King's College London, London, UK
| | - J Canales
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - M J Costas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - J M Ribeiro
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - J R Rodrigues
- Laboratório Associado LSRE-LCM, Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Leiria, Leiria, Portugal
| | - M A McAleer
- Paediatric Dermatology, Children's Health Ireland at Crumlin, Dublin, Ireland
| | - L Castelo-Soccio
- Pediatric Dermatology, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - M A Simpson
- Department of Medical and Molecular Genetics, School of Basic and Medical Biosciences, Guy's Hospital, King's College London, London, UK
| | - F Fraternali
- Randall Centre for Cell and Molecular Biophysics, Guy's Hospital, King's College London, London, UK
| | - A D Irvine
- Paediatric Dermatology, Children's Health Ireland at Crumlin, Dublin, Ireland.,Clinical Medicine, Trinity College Dublin, Dublin, Ireland
| | - J C Cameselle
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - J A McGrath
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, Guy's Hospital, King's College London, London, UK
| |
Collapse
|
3
|
Hanson AD, Beaudoin GA, McCarty DR, Gregory JF. Does Abiotic Stress Cause Functional B Vitamin Deficiency in Plants? PLANT PHYSIOLOGY 2016; 172:2082-2097. [PMID: 27807106 PMCID: PMC5129723 DOI: 10.1104/pp.16.01371] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/19/2016] [Indexed: 05/20/2023]
Abstract
B vitamins are the precursors of essential metabolic cofactors but are prone to destruction under stress conditions. It is therefore a priori reasonable that stressed plants suffer B vitamin deficiencies and that certain stress symptoms are metabolic knock-on effects of these deficiencies. Given the logic of these arguments, and the existence of data to support them, it is a shock to realize that the roles of B vitamins in plant abiotic stress have had minimal attention in the literature (100-fold less than hormones) and continue to be overlooked. In this article, we therefore aim to explain the connections among B vitamins, enzyme cofactors, and stress conditions in plants. We first outline the chemistry and biochemistry of B vitamins and explore the concept of vitamin deficiency with the help of information from mammals. We then summarize classical and recent evidence for stress-induced vitamin deficiencies and for plant responses that counter these deficiencies. Lastly, we consider potential implications for agriculture.
Collapse
Affiliation(s)
- Andrew D Hanson
- Horticultural Sciences Department (A.D.H., G.A.B., D.R.M) and Food Science and Human Nutrition Department (J.F.G.), University of Florida, Gainesville, Florida 32611-0690
| | - Guillaume A Beaudoin
- Horticultural Sciences Department (A.D.H., G.A.B., D.R.M) and Food Science and Human Nutrition Department (J.F.G.), University of Florida, Gainesville, Florida 32611-0690
| | - Donald R McCarty
- Horticultural Sciences Department (A.D.H., G.A.B., D.R.M) and Food Science and Human Nutrition Department (J.F.G.), University of Florida, Gainesville, Florida 32611-0690
| | - Jesse F Gregory
- Horticultural Sciences Department (A.D.H., G.A.B., D.R.M) and Food Science and Human Nutrition Department (J.F.G.), University of Florida, Gainesville, Florida 32611-0690
| |
Collapse
|
4
|
Proteomic changes associated with metabolic syndrome in a fructose-fed rat model. J Food Drug Anal 2016; 24:754-761. [PMID: 28911613 PMCID: PMC9337292 DOI: 10.1016/j.jfda.2016.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/16/2016] [Accepted: 03/23/2016] [Indexed: 01/01/2023] Open
Abstract
Metabolic syndrome (MetS), characterized by a constellation of disorders such as hyperglycemia, insulin resistance, and hypertension, is becoming a major global public health problem. Fructose consumption has increased dramatically over the past several decades and with it the incidence of MetS. However, its molecular mechanisms remain to be explored. In this study, we used male Sprague-Dawley (SD) rats to study the pathological mechanism of fructose induced MetS. The SD rats were fed a 60% high-fructose diet for 16 weeks to induce MetS. The induction of MetS was confirmed by blood biochemistry examination. Proteomics were used to investigate the differential hepatic protein expression patterns between the normal group and the MetS group. Proteomic results revealed that fructose-induced MetS induced changes in glucose and fatty acid metabolic pathways. In addition, oxidative stress and endoplasmic reticulum stress-related proteins were modulated by high-fructose feeding. In summary, our results identify many new targets for future investigation. Further characterization of these proteins and their involvement in the link between insulin resistance and metabolic dyslipidemia may bring new insights into MetS.
Collapse
|
5
|
Mishanina TV, Yu L, Karunaratne K, Mondal D, Corcoran JM, Choi MA, Kohen A. An unprecedented mechanism of nucleotide methylation in organisms containing thyX. Science 2016; 351:507-10. [PMID: 26823429 DOI: 10.1126/science.aad0300] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In several human pathogens, thyX-encoded flavin-dependent thymidylate synthase (FDTS) catalyzes the last step in the biosynthesis of thymidylate, one of the four DNA nucleotides. ThyX is absent in humans, rendering FDTS an attractive antibiotic target; however, the lack of mechanistic understanding prohibits mechanism-based drug design. Here, we report trapping and characterization of two consecutive intermediates, which together with previous crystal structures indicate that the enzyme's reduced flavin relays a methylene from the folate carrier to the nucleotide acceptor. Furthermore, these results corroborate an unprecedented activation of the nucleotide that involves no covalent modification but only electrostatic polarization by the enzyme's active site. These findings indicate a mechanism that is very different from thymidylate biosynthesis in humans, underscoring the promise of FDTS as an antibiotic target.
Collapse
Affiliation(s)
| | - Liping Yu
- Nuclear Magnetic Resonance (NMR) Core Facility and Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | | | - Dibyendu Mondal
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
| | - John M Corcoran
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Michael A Choi
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Amnon Kohen
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
6
|
Rodrigues JR, Couto A, Cabezas A, Pinto RM, Ribeiro JM, Canales J, Costas MJ, Cameselle JC. Bifunctional homodimeric triokinase/FMN cyclase: contribution of protein domains to the activities of the human enzyme and molecular dynamics simulation of domain movements. J Biol Chem 2014; 289:10620-10636. [PMID: 24569995 DOI: 10.1074/jbc.m113.525626] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mammalian triokinase, which phosphorylates exogenous dihydroxyacetone and fructose-derived glyceraldehyde, is neither molecularly identified nor firmly associated to an encoding gene. Human FMN cyclase, which splits FAD and other ribonucleoside diphosphate-X compounds to ribonucleoside monophosphate and cyclic X-phosphodiester, is identical to a DAK-encoded dihydroxyacetone kinase. This bifunctional protein was identified as triokinase. It was modeled as a homodimer of two-domain (K and L) subunits. Active centers lie between K1 and L2 or K2 and L1: dihydroxyacetone binds K and ATP binds L in different subunits too distant (≈ 14 Å) for phosphoryl transfer. FAD docked to the ATP site with ribityl 4'-OH in a possible near-attack conformation for cyclase activity. Reciprocal inhibition between kinase and cyclase reactants confirmed substrate site locations. The differential roles of protein domains were supported by their individual expression: K was inactive, and L displayed cyclase but not kinase activity. The importance of domain mobility for the kinase activity of dimeric triokinase was highlighted by molecular dynamics simulations: ATP approached dihydroxyacetone at distances below 5 Å in near-attack conformation. Based upon structure, docking, and molecular dynamics simulations, relevant residues were mutated to alanine, and kcat and Km were assayed whenever kinase and/or cyclase activity was conserved. The results supported the roles of Thr(112) (hydrogen bonding of ATP adenine to K in the closed active center), His(221) (covalent anchoring of dihydroxyacetone to K), Asp(401) and Asp(403) (metal coordination to L), and Asp(556) (hydrogen bonding of ATP or FAD ribose to L domain). Interestingly, the His(221) point mutant acted specifically as a cyclase without kinase activity.
Collapse
Affiliation(s)
- Joaquim Rui Rodrigues
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain; Escola Superior de Tecnologia e Gestão, Instituto Politécnico de Leiria, P-2411-901 Leiria, Portugal
| | - Ana Couto
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - Alicia Cabezas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - Rosa María Pinto
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - João Meireles Ribeiro
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - José Canales
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - María Jesús Costas
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain
| | - José Carlos Cameselle
- Grupo de Enzimología, Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Medicina, Universidad de Extremadura, E-06006 Badajoz, Spain.
| |
Collapse
|
7
|
Abstract
(1)H-, (11)B-, (13)C-, (15)N-, (17)O-, (19)F-, and (31)P-NMR chemical shifts of flavocoenzymes and derivatives of it, as well as of alloxazines and isoalloxazinium salts, from NMR experiments performed under various experimental conditions (e.g., dependence of the chemical shifts on temperature, concentration, solvent polarity, and pH) are reported. Also solid-state (13)C- and (15)N-NMR experiments are described revealing the anisotropic values of corresponding chemical shifts. These data, in combination with a number of coupling constants, led to a detailed description of the electronic structure of oxidized and reduced flavins. The data also demonstrate that the structure of oxidized flavin can assume a configuration deviating from coplanarity, depending on substitutions in the isoalloxazine ring, while that of reduced flavin exhibits several configurations, from almost planar to quite bended. The complexes formed between oxidized flavin and metal ions or organic molecules revealed three coordination sites with metal ions (depending on the chemical nature of the ion), and specific interactions between the pyrimidine moiety of flavin and organic molecules, mimicking specific interactions between apoflavoproteins and their coenzymes. Most NMR studies on flavoproteins were performed using (13)C- and (15)N-substituted coenzymes, either specifically enriched in the pterin moiety of flavin or uniformly labeled flavins. The chemical shifts of free flavins are used as a guide in the interpretation of the chemical shifts observed in flavoproteins. Although the hydrogen-bonding pattern in oxidized and reduced flavoproteins varies considerably, no correlation is obvious between these patterns and the corresponding redox potentials. In all reduced flavoproteins the N(1)H group of the flavocoenzyme is deprotonated, an exception is thioredoxin reductase. Three-dimensional structures of only a few flavoproteins, mostly belonging to the family of flavodoxins, have been solved. Also the kinetics of unfolding and refolding of flavodoxins has been investigated by NMR techniques. In addition, (31)P-NMR data of all so far studied flavoproteins and some (19)F-NMR spectra are discussed.
Collapse
Affiliation(s)
- Franz Müller
- , Wylstrasse 13, CH-6052, Hergiswil, Switzerland,
| |
Collapse
|
8
|
Lapalikar GV, Taylor MC, Warden AC, Onagi H, Hennessy JE, Mulder RJ, Scott C, Brown SE, Russell RJ, Easton CJ, Oakeshott JG. Cofactor promiscuity among F420-dependent reductases enables them to catalyse both oxidation and reduction of the same substrate. Catal Sci Technol 2012. [DOI: 10.1039/c2cy20129a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
9
|
Sánchez-Moreno I, Iturrate L, Martín-Hoyos R, Jimeno ML, Mena M, Bastida A, García-Junceda E. From kinase to cyclase: an unusual example of catalytic promiscuity modulated by metal switching. Chembiochem 2009; 10:225-9. [PMID: 19058275 DOI: 10.1002/cbic.200800573] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Israel Sánchez-Moreno
- Departamento de Química Orgánica Biológica, Instituto de Química Orgánica General, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
10
|
Cabezas A, Costas MJ, Pinto RM, Couto A, Cameselle JC. Identification of human and rat FAD-AMP lyase (cyclic FMN forming) as ATP-dependent dihydroxyacetone kinases. Biochem Biophys Res Commun 2005; 338:1682-9. [PMID: 16289032 DOI: 10.1016/j.bbrc.2005.10.142] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 10/24/2005] [Indexed: 10/25/2022]
Abstract
Rat liver FAD-AMP lyase or FMN cyclase is the only known enzymatic source of the unusual flavin nucleotide riboflavin 4',5'-cyclic phosphate. To determine its molecular identity, a peptide-mass fingerprint of the purified rat enzyme was obtained. It pointed to highly related, mammalian hypothetical proteins putatively classified as dihydroxyacetone (Dha) kinases due to weaker homologies to biochemically proven Dha kinases of plants, yeasts, and bacteria. The human protein LOC26007 cDNA was used to design PCR primers. The product amplified from human brain cDNA was cloned, sequenced (GenBank Accession No. ), and found to differ from protein LOC26007 cDNA by three SNPs. Its heterologous expression yielded a protein active both as FMN cyclase and ATP-dependent Dha kinase, each activity being inhibited by the substrate(s) of the other. Cyclase and kinase activities copurified from rat liver extracts. Evidence supports that a single protein sustains both activities, probably in a single active center. Putative Dha kinases from other mammals are likely to be FMN cyclases too. Future work will profit from the availability of the structure of Citrobacter freundii Dha kinase, which contains substrate-interacting residues conserved in human Dha kinase/FMN cyclase.
Collapse
Affiliation(s)
- Alicia Cabezas
- Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Extremadura, 06080 Badajoz, Spain
| | | | | | | | | |
Collapse
|
11
|
Canales J, Cabezas A, Pinto RM, Cameselle JC. Fluorimetric HPLC detection of endogenous riboflavin 4',5'-cyclic phosphate in rat liver at nanomolar concentrations. Anal Biochem 2005; 341:214-9. [PMID: 15907866 DOI: 10.1016/j.ab.2005.01.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Indexed: 10/25/2022]
Abstract
We have investigated the biological occurrence of riboflavin 4',5'-cyclic phosphate (cyclic FMN or cFMN), the flavin product known to be formed in vitro from FAD by the rat liver enzyme FAD-AMP lyase (cyclizing) or FMN cyclase (EC 4.6.1.15). The expected difficulties were the low concentration of the compound, the tendency of the more abundant FAD to decompose chemically to cFMN, and the acid lability of cFMN itself. A protocol was devised to prepare deproteinized rat liver extracts, avoiding conditions prone to the chemical formation of cFMN and making exposure to conditions of cFMN degradation as short as possible. In these extracts, cFMN was assayed by HPLC with fluorimetric detection. The identity of liver cFMN was confirmed by its HPLC separation from other known flavins, its coelution with authentic cFMN, and its susceptibility to acid degradation, yielding a mixture of 5'-FMN and 4'-FMN. The amount of total cFMN recovered in the liver extracts was 22+/-11 pmol/g fresh tissue. Careful control experiments were performed to rule out the possibility that this could be a chemical product of FAD degradation during extract preparation. These controls indicated that, on average, 97% of the measured extract concentration of cFMN, i.e., about 21+/-10 pmol/g, was already present in the liver at the beginning of the process and was extracted from the tissue. This figure is likely to be an underestimation of the hepatic content, as indicated by control experiments.
Collapse
Affiliation(s)
- José Canales
- Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Extremadura, 06080 Badajoz, Spain
| | | | | | | |
Collapse
|
12
|
Chienthavorn O, Smith RM, Saha S, Wilson ID, Wright B, Taylor SD, Lenz EM. Superheated water chromatography-nuclear magnetic resonance spectroscopy and mass spectrometry of vitamins. J Pharm Biomed Anal 2004; 36:477-82. [PMID: 15522520 DOI: 10.1016/j.jpba.2004.07.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2004] [Accepted: 07/18/2004] [Indexed: 10/26/2022]
Abstract
The water-soluble vitamins, pyridoxine, riboflavin, and thiamine, were separated by reversed-phase liquid chromatography using hot or superheated water as the mobile phase and were detected using a range of detectors, including ultraviolet and fluorescence spectroscopy and mass spectrometry. By using deuterium oxide as the eluent, direct on-line nuclear magnetic resonance spectra could be obtained with minimal spectral interference from the mobile phase. Some of the compounds showed deuterium exchange of alkyl-protons when separated at high temperatures.
Collapse
Affiliation(s)
- Orapin Chienthavorn
- Department of Chemistry, Loughborough University, Loughborough, Leics LE11 3TU, UK
| | | | | | | | | | | | | |
Collapse
|
13
|
Cabezas A, Pinto RM, Fraiz F, Canales J, González-Santiago S, Cameselle JC. Purification, characterization, and substrate and inhibitor structure-activity studies of rat liver FAD-AMP lyase (cyclizing): preference for FAD and specificity for splitting ribonucleoside diphosphate-X into ribonucleotide and a five-atom cyclic phosphodiester of X, either a monocyclic compound or a cis-bicyclic phosphodiester-pyranose fusion. Biochemistry 2001; 40:13710-22. [PMID: 11695920 DOI: 10.1021/bi0157159] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An enzyme with FAD-AMP lyase (cyclizing) activity, splitting FAD to AMP and riboflavin 4',5'-phosphate (cFMN), was recently identified [Fraiz, F., et al. (1998) Biochem. J. 330, 881-888]. Now, it has been purified to apparent homogeneity from a rat liver supernatant, by a procedure that includes affinity for ADP-agarose (adsorption required the activating cation Mn2+ and desorption required its removal), to a final activity of 2.2 units/mg after a 240-fold purification with a 15% yield. By SDS-PAGE, only one protein band was observed (Mr = 59 000). The correspondence between protein and enzyme activity was demonstrated by renaturation after SDS-PAGE, by gradient ultracentrifugation followed by analytical SDS-PAGE, and by native PAGE with visualization of enzyme activity by fluorescence. A native Mr of 100 000 (ultracentrifugation) or 140 000 (gel filtration) indicated that FAD-AMP lyase could be a dimer. The enzyme required millimolar concentrations of Mn2+ or Co2+, exhibited different optimum pH values with these cations (pH 8.5 or 7.3, respectively), and was strongly inhibited by ADP or ATP, but not by dADP, dATP, or the reaction products AMP and cFMN. A specificity study was conducted with 35 compounds related to FAD, mostly nucleoside diphosphate-X (NDP-X) derivatives. Besides FAD, the enzyme split 11 of these compounds with the pattern NDP-X --> NMP + P=X. Structure-activity correlations of substrates, nonsubstrates, and inhibitors, and the comparison of the enzymic reactivities of NDP-X compounds with their susceptibilities to metal-dependent chemical degradation, pinpointed the following specificity pattern. FAD-AMP lyase splits ribonucleoside diphosphate-X compounds in which X is an acyclic or cyclic monosaccharide or derivative bearing an X-OH group that is able to attack internally the proximal phosphorus with the geometry necessary to form a P=X product, either a five-atom monocyclic phosphodiester or a cis-bicyclic phosphodiester-pyranose fusion. For instance, NDP-glucose and GDP-alpha-L-fucose were substrates, but dTDP-glucose, NDP-mannose, and GDP-beta-L-fucose were not. Judging from kcat/Km ratios, we found the best substrate to be FAD, followed closely by ADP-glucose (kcat/Km only 2-fold lower, but not a physiological compound in mammals), whereas other substrates exhibited 50-500-fold lower kcat/Km values. However, there was no evidence for specific flavin recognition. Instead, what seems to be recognized is the NDP moiety of NDP-X, with a strong preference for ADP-X. Splitting would then depend on the presence of an adequate X-OH group. The possibility that, besides FAD, there could be in mammals other ADP-X substrates of FAD-AMP lyase is discussed, with emphasis placed on some ADP-ribose derivatives.
Collapse
Affiliation(s)
- A Cabezas
- Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Extremadura, Apartado de Correos 108, E-06080 Badajoz, Spain
| | | | | | | | | | | |
Collapse
|
14
|
Pinto RM, Fraiz FJ, Cabezas A, Avalos M, Canales J, Costas MJ, Cameselle JC. Preparation of riboflavin 4',5'-cyclic phosphate by incubation of flavin-adenine dinucleotide with Mn2+ in the absence of riboflavin 5'-phosphate cyclase. Anal Biochem 1999; 268:409-11. [PMID: 10075835 DOI: 10.1006/abio.1998.3063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- R M Pinto
- Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Extremadura, Apartado 108, Badajoz, E-06080, Spain
| | | | | | | | | | | | | |
Collapse
|