1-Fluoro-2,4-dinitrobenzene (commonly called Sanger's reagent , dinitrofluorobenzene , DNFB or FDNB ) is a chemical that reacts with the N-terminal amino acid of polypeptides . This can be helpful for sequencing proteins .
8-558: In 1936, Gottlieb presented a synthesis in which 1-chloro-2,4-dinitrobenzene reacted with potassium fluoride (KF) in nitrobenzene : In 1945, Frederick Sanger described its use for determining the N-terminal amino acid in polypeptide chains, in particular insulin . Sanger's initial results suggested that insulin was a smaller molecule than previously estimated (molecular weight 12,000), and that it consisted of four chains (two ending in glycine and two ending in phenylalanine ), with
16-424: A combination of crown ether and bulky diols in acetonitrile solvent. Potassium fluoride on alumina (KF/Al 2 O 3 ) is a base used in organic synthesis. It was originally introduced in 1979 by Ando et al. for inducing alkylation reactions. It is Like other sources of the fluoride ion, F , KF is poisonous, although lethal doses approach gram levels for humans. It is harmful by inhalation and ingestion. It
24-424: Is prepared by reacting potassium carbonate with hydrofluoric acid . Evaporation of the solution forms crystals of potassium bifluoride . The bifluoride on heating yields potassium fluoride: Platinum or heat resistant plastic containers are often used for these operations. Potassium chloride converts to KF upon treatment with hydrogen fluoride. In this way, potassium fluoride is recyclable. KF crystallizes in
32-400: Is the chemical compound with the formula KF . After hydrogen fluoride , KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide salt and occurs naturally as the rare mineral carobbiite . Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective. Potassium fluoride
40-403: The chains cross-linked by disulfide bonds . Sanger continued work on insulin, using dinitrofluorobenzene in combination with other techniques, eventually resulted in the complete sequence of insulin (consisting of only two chains, with a molecular weight of 6,000). Following Sanger's initial report of the reagent, the dinitrofluorobenzene method was widely adopted for studying proteins, until it
48-520: The cubic NaCl crystal structure . The lattice parameter at room temperature is 0.266 nm. In organic chemistry , KF can be used for the conversion of chlorocarbons into fluorocarbons , via the Finkelstein (alkyl halides) and Halex reactions (aryl chlorides). Such reactions usually employ polar solvents such as dimethyl formamide , ethylene glycol , and dimethyl sulfoxide . More efficient fluorination of aliphatic halides can be achieved with
56-452: The identity of those amino acids can be discovered through chromatography . More recently, Sanger's reagent has also been used for the rather difficult analysis of distinguishing between the reduced and oxidized forms of glutathione and cysteine in biological systems in conjunction with HPLC. This method is robust enough that it can be performed in such complex matrices as blood or cell lysate. Potassium fluoride Potassium fluoride
64-476: Was superseded by other reagents for terminal analysis (e.g., dansyl chloride and later aminopeptidases and carboxypeptidases ) and other general methods for sequence determination (e.g., Edman degradation ). Dinitrofluorobenzene reacts with the amine group in amino acids to produce dinitrophenyl -amino acids. These DNP-amino acids are moderately stable under acid hydrolysis conditions that break peptide bonds . The DNP-amino acids can then be recovered, and
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