ASSESSMENT OF PROTEIN CONFORMATION IN HUMAN BENIGN AND MALIGNANT ASTROCYTOMAS BY REFLECTANCE FOURIER-TRANSFORM INFRARED MICROSPECTROSCOPY

The secondary structure and composition of protein in the tissues of b enign and malignant astrocytomas were determined by reflectance Fourie r-transform infrared (FT-IR) microspectroscopy. The peak maximum of IR spectra of the tissues from recurrent malignant astrocytoma markedly appeared at higher frequency (1655 or 1663 cm(-1)), which was signific antly different from that of the tissues from benign astrocytoma at 16 51 cm(-1) and tissues from malignant astrocytoma at 1652 cm(-1). Malig nant astrocytoma indicated slightly different compositions in the prot ein secondary structure from benign astrocytoma. However, a significan t increase in beta-turn structure but a marked decrease in beta-sheet and random coil structures were observed in the protein secondary stru cture of the recurrent malignant astrocytoma. The phenomenon was more pronounced in recurrent malignant astrocytoma pretreated with radiatio n and chemotherapy. The rapid cell proliferation and cell differentiat ion of malignant astrocytoma with or without recurrence might be the p ossible explanations for the different compositions of protein conform ational structures.