Study on the secondary structure of protein in amide I band from human colon cancer tissue by Fourier-transform infrared spectroscopy.
BACKGROUND
Fourier-transform infrared spectroscopy (FT-IR) is a powerful tool for study of the secondary conformation of intact protein in biological tissues and for diagnosis of disease states. The purpose of this study is to utilize FT-IR as a diagnostic tool to estimate the secondary structure of amide I in normal and cancer tissue of human colon.


METHODS
Pairs of tissue samples from colon cancer and histologically normal mucosa tissue 5-10 cm from the tumor were obtained from a patient who underwent partial colectomy. In the present study we investigated the changes in the secondary structure of amide I of normal and malignant human colon tissue using FT-IR microspectroscopy with attenuated total reflectance. Secondary-derivative analysis relative to the original and curve-fitting analysis infrared spectra were also carried out.


RESULTS
The conformational changes of the secondary structure of protein in normal and cancerous human colon tissue were (1) the composition of alpha-helixes increased in human cancerous colon tissue (15.30%) compared to normal colon tissue (11.72%); (2) beta-sheets which were 46.8% in healthy tissue decreased to 30.71% in cancer tissue; (3) beta-turns increased from 26.28% in normal tissue to 38.48% in cancer tissue; and (4) the composition of random coils was not significantly different between normal tissue (15.12%) and cancer tissue (15.51%).


CONCLUSIONS
Our data demonstrate that protein in colon cancer displays abnormal FT-IR spectra. The conformational changes of the secondary structure of this protein in terms of alpha-helixes, beta-sheets and beta-turns were observed in normal and cancerous tissue from the same individual were compared.
Chen
Y J
YJ
Department of Internal Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan, R.O.C.
Hsieh
Y W
YW
Cheng
Y D
YD
Liao
C C
CC
D000368:Aged; D000577:Amides / Q000737:chemistry; D003110:Colonic Neoplasms / Q000737:chemistry*; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
D000577:Amides; D009363:Neoplasm Proteins