Observation of the Adsorption of Cytochrome c and Glucose Oxidase onto an Amphiphilic Monolayer at an Air/Water Interface by the Reflection Spectroscopy of Visible Radiation

Abstract

The adsorption of two kinds of chromoproteins, cytochrome c and glucose oxidase, was observed at an air/water interface by reflection spectroscopy using optical fibers. The relation between the adsorption of cytochrome c onto an amphiphilic monolayer and the deposition of the monolayer with cytochrome c by the Langmuir–Blodgett (LB) technique was clarified. It was found out that a good Y-type LB film, with a transfer ratio of 0.9—1.0, was obtained when the adsorbed area of cytochrome c was less than about 84% of the maximum average coverage. The reflection spectrum of glucose oxidase, not as such, but stained with coomassie brilliant blue (CBB), could be successfully observed. Since CBB is applicable to almost any protein, the reflection spectroscopy of almost any protein, not only chromoproteins, is possible.

UV-Vis reflection spectroscopy under variable angle incidence at the air–liquid interface

“…This technique is an extremely useful tool in different cases of study, which concerns both the study of Gibbs 4 and Langmuir monolayers. 5 Thus, UV-Vis-RS has been used for studying the interactions of various soluble components in the aqueous subphase, such as drugs, 6,7 proteins [8][9][10] and polyelectrolytes, [11][12][13] with ordered lipid Langmuir monolayers. Additionally, the study of ionic interactions, [14][15][16][17][18] molecular recognition, [19][20][21][22] and inclusion complex formation, 23 and analysis of phenomena such as photochromic, [24][25][26] photoisomerization, [27][28][29][30][31][32][33] charge and energy transfer, [34][35][36][37][38][39] and photoinduced electron-transfer [40][41][42][43] at the air-liquid interface have greatly benefited from the use of UV-Vis-RS.…”