SECONDARY STRUCTURE OF TUBULIN ON THE EVI DENCE OF FOURIER-TRANSFORM INFRARED-SPECTROSCOPY INVESTIGATION

Fourier transform infrared technique is used for identifying secondary structure of GTP/GDP tubulin in the absorbancy region of its amide-I band. With this technique the band was initially resolved for 3 main a nd 4 satellite maxima, subsequently taken as starting values for compu ter resolution of the band into components of Gaussian line shape. A r esolution of the spectrum into components was carried out with the FUM ILI software; the resolution error was 1,5%. Improved maxima positions for the resolved components of GTP tubulin spectrum are as follows: 1 682,2; 1663,7; 1653,2; 1633,4; 1625,4; 1614,0; 1605,7 cm(-1) each assi gned to the vibrations of a definite structural type of the protein. T he main part of the structure, similar to 50%, corresponds to beta-ant iparallel sheet, the contribution of alpha-coils is about of 25%. GDP tubulin shows the contribution of beta-antiparallel sheet to be greate r and the contribution of alpha-coil to be less than in GTP tubulin. T he difference in the maxima positions of GTP and GDP tubulin spectra d oes not exceed the value of +/-3 cm(-1).