Fluorescent thiol reagents. VI. N-(1-Anilinonaphthyl-4)maleimide; a fluorescent hydrophobic probe directed to thiol groups in protein

N-(1-Anilinonaphthyl-4)maleimide (ANM) (m.p. 207-208.5 degrees C), nonfluorescent, reacts selectively with thiols to give addition products which are strongly fluorescent (excitation maximum 355 nm, emission maximum 448 nm, in ethanol). 0.7 mole of ANM was introduced into thiol groups of egg albumin without modifying any other amino acid residues. In the fluorescence spectra of the reaction products of ANM with thiols, the quantum yields increase and the emission maxima shift towards the blue as the solvent polarity decreases. This remarkable solvent dependence was described in terms ofZ value of the solvents. ANM is thus expected to be a useful fluorescent hydrophobic probe directed to thiol groups in protein.

Electrophoresis of guinea-pig complement components (C3, C5, C6, C7, C8 and C9) on polyacrylamide gel

The electrophoretic mobilities of C3, C5, C6, C7, C8 and C9 of guinea-pig complement were studied using polyacrylamide (PAA) gel as a supporting medium. The haemolytic activity of each complement component was readily revealed as a discrete haemolytic band in blood agar containing intermediate red blood cells and appropriate reagents which was overlayed on the PAA gel plate after electrophoresis. By this method, the relative mobilities of C3, C5, C6, C7, C8 and C9 were determined as 0.19, 0.40, 0.17, 0.27, 0.31 and 0.57 respectively. An additional, distinct, haemolytic C5 band was detected when native guinea-pig serum was run. The relative mobility of the haemolytic activity which was not detected when purified C5 was electrophoresed, was 0.25.