2-methoxy-2,4-diphenyl-3 -furanone

Dipping solution Dissolve 25 mg 2-methoxy-2,4-diphenyl-3(2H)-furanone in 50 ml methanol. 

Both pre- and post-electrophoresis staining can be done. However, post-staining usually is preferred, because it does not alter the separation. Anilinonaphthalene sulfonate can detect 20 pg of protein. Dansyl chloride reacts with amines, amino acids, proteins, and phenols. Exposure of protein for 1 to 2 minutes at 100 °C to dansyl chloride produces a fluorescence capable of detecting 8 to 10 ng. Similarly, exposing primary amine-containing compounds to fluor-escamine at room temperature and an alkaline pH permits the detection of 6 ng of myoglobin. A newly popular compound is 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF). It can detect 1 ng of protein, and it is linear from 1 to 500 ng. 

Chemists, International MDFF 2-Methoxy-2,4-diphenyl-3-(2//)-furanone... 

Two new chromophoric reagents, 2-methoxy-2,4-diphenyl-3(2/f)-furanone (MDPF) (49) and 4-phenylspiro[furan-2(3H)-r-phthalan]-3,3 -dione (fluorescamine, trade name Fluram) (50) were introduced for the correlation of... 

Methoxy-2-diphenyl-3(2//)-furanone, which is structurally related to fluorescamine, has the same unique properties. The reaction of MDPF with primary amines proceeds rapidly only above pH 9 (Weigele et al, 1973). Much higher reagent concentrations are often required, e.g., 10 mg/ml, in order to obtain nearly quantitative fluorophor formation (Wideman et al, 1978). This requirement is due to the more rapid hydrolysis of MDPF. In contrast with fluorescamine, MDPF dissolved in methanol is as stable and as reactive as when it is dissolved in acetone. The MDPF fluorophors also have excitation and emission maxima at 390 and 475 nm, respectively. Various peptide fluorophors have been found to be stable between pH 2 and 11, and it has been possible to lyophilize the fluorophors without any decomposition. The fluorescence intensity also varies with solvent composition, but not with pH. 

In SDS electrophoresis, the proteins can be prelabeled with dyes that covalently bind to their NH residues. The dyes can be conventional (e.g., the blue dye Remazol) or fluorescent, such as dansyl chloride, fluore.scamine. O-phthaldialde-hyde. and MDPF (2-methoxy-2,4-diphenyl-3[2//]-furanone). Prelabeling is compatible with SDS electrophoresis, as the size increase is minimal, but would be disastrous in di.sc electrophoresis or lEF, as it would generate a series of bands of slightly altered mobility or pi from an otherwise homogeneous protein. 

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