Abstract: Soy protein isolates were prepared from soybean by methods of ultrafiltration and sediment at isoelectric pH. The SDS-PAGE patterns of sognilk, defatted soybean and soy protein isolates smples were analyzed. 17 bands of soy proteins were fed in all of the SDS-PAGE patterns.In all of the propared smples, band l7 with ar 104620 was formed as the only new one and some thermal sensitive bands such as band 13 with Mr 76060, band 12 with ar 70740 and band 5 with Mr 32820 disappeared. It was found ty heating and β -mercaptoethanol treatment that the change of sulfhydryl bond was attributed to this coanon SDS-PAGE pattern change. The SDS-PAGE patterns of soy protein also exited some changes when soybean was prepared as defatted soybean and protein isolates- sand 1 in defatted soybean, band 4, 7 in the protein isolates produced by sediment at isoelectric pH and band 1, 2 in the protein isolates produced by ultrafiltration were found disrmeared. The various characteristics chanqes were related to these changes processing.

Key words: Soybean Soy protein isolates SDS-PAGE