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Sheraz MA, Kazi SH, Ahmed S, Anwar Z, Ahmad I. Photo, thermal and chemical degradation of riboflavin. Beilstein J Org Chem 2014; 10:1999-2012. [PMID: 25246959 PMCID: PMC4168737 DOI: 10.3762/bjoc.10.208] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 08/14/2014] [Indexed: 02/02/2023] Open
Abstract
Riboflavin (RF), also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also been identified that affect the stability of RF. These factors include radiation source, its intensity and wavelength, pH, presence of oxygen, buffer concentration and ionic strength, solvent polarity and viscosity, and use of stabilizers and complexing agents. A detailed review of the literature in this field has been made and all those factors that affect the photo, thermal and chemical degradation of RF have been discussed. RF undergoes degradation through several mechanisms and an understanding of the mode of photo- and thermal degradation of RF may help in the stabilization of the vitamin. A general scheme for the photodegradation of RF is presented.
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Affiliation(s)
- Muhammad Ali Sheraz
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan
| | - Sadia Hafeez Kazi
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan
| | - Sofia Ahmed
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan
| | - Zubair Anwar
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan
| | - Iqbal Ahmad
- Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan
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Grininger M, Staudt H, Johansson P, Wachtveitl J, Oesterhelt D. Dodecin is the key player in flavin homeostasis of archaea. J Biol Chem 2009; 284:13068-76. [PMID: 19224924 DOI: 10.1074/jbc.m808063200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Flavins are employed to transform physical input into biological output signals. In this function, flavins catalyze a variety of light-induced reactions and redox processes. However, nature also provides flavoproteins with the ability to uncouple the mediation of signals. Such proteins are the riboflavin-binding proteins (RfBPs) with their function to store riboflavin for fast delivery of FMN and FAD. Here we present in vitro and in vivo data showing that the recently discovered archaeal dodecin is an RfBP, and we reveal that riboflavin storage is not restricted to eukaryotes. However, the function of the prokaryotic RfBP dodecin seems to be adapted to the requirement of a monocellular organism. While in eukaryotes RfBPs are involved in trafficking riboflavin, and dodecin is responsible for the flavin homeostasis of the cell. Although only 68 amino acids in length, dodecin is of high functional versatility in neutralizing riboflavin to protect the cellular environment from uncontrolled flavin reactivity. Besides the predominant ultrafast quenching of excited states, dodecin prevents light-induced riboflavin reactivity by the selective degradation of riboflavin to lumichrome. Coordinated with the high affinity for lumichrome, the directed degradation reaction is neutral to the cellular environment and provides an alternative pathway for suppressing uncontrolled riboflavin reactivity. Intriguingly, the different structural and functional properties of a homologous bacterial dodecin suggest that dodecin has different roles in different kingdoms of life.
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Affiliation(s)
- Martin Grininger
- Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
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Müller U, Willnow P, Ruschig U, Höpner T. Formate dehydrogenase from Pseudomonas oxalaticus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1978; 83:485-98. [PMID: 631130 DOI: 10.1111/j.1432-1033.1978.tb12115.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Formate dehydrogenase (EC 1.2.1.2) from Pseudomonas oxalaticus has been isolated and characterized. The enzyme (molecular weight 315000) is a complex flavoprotein containing 2 FMN, 18--25 non-heme iron atoms and 15--20 acid-labile sulphides. In the last step of the purification, a sucrose gradient centrifugation, a second catalytically active species has been found apparently originating from a dissociation of the enzyme into two equal subunits. The enzyme is specific toward its natural substrate formate. It transfers electrons to NAD+, oxygen, ferricyanide, and a lot of nonphysiological acceptors (dyes). In addition electrons are transferred from NADH to these acceptors. The (reversible) removal of FMN requires a reduction step. Reincorporation has been followed by the reappearance of the reactivity against formate and by fluorescence titration. The deflavo enzyme also binds FAD and riboflavin. The resulting enzyme species show characteristic catalytic abilities. Activity against formate is peculiar to the FMN species.
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