<title>Spectral properties of glycated and native albumins</title>

Abstract

Albumin is an important protein and its glycated form increases in diabetes mellitus and is partly responsible for the age related phenomena. We have, therefore, investigated the optical absorption and fluorescence spectra of glycated albumin along with a kinetic study by means of a proteolytic reaction. For this purpose, albumin was glycated by a conventional method and the optical absorption spectra were recorded for both the glycated and the native forms, from 240 nm to 400 nm and found that they were dominated by a strong peak at 280 nm which was followed by a long tail up to 300 nm for the native and 400 nm for the glycated protein. Non tryptophane fluorescence spectra of both glycated and native albumins in solid form were investigated and it was found that the general features of both spectra are similar. The spectra are dominated by a weak peak located at 450 nm and an intense broad peak at 550 nm. This peak is followed by a shoulder at 625 nm and then a long tail up to 800 nm. One of the major effects of glycation in this investigation is in their physical forms. Native albumin has a crystalline form while the glycated one has a conglomerate form. This effect can be easily visualized when the sample is examined with the help of a fluorescence microscope. This result is in accordance with the data obtained from electron microscopy. Thus, this quick and direct approach could identify the presence of the glycated protein and could provide information on the pathology of diabetes art an early stage.