Change of soybean isolate poypeptide composition during thermal inactivation of trypsin inhibitors

Abstract

The change of polypeptide composition of soybean isolates, prepared from samples treated by autoclaving in the aim of trypsin inhibitors inactivation (0.5 bar; 5,10 and 15 min.) was investigated. By densitometric analysis of SDS-PAGE-gels, the composition of soybean isolated protein was determined. According to our results, glycinin showed the highest content among proteins of soybean isolates. Depending on duration of soybeans heating, the percentage of glycinin in resulting isolate was 47.14-53.08%. High content of acidic (30.02-30.98%) and basic (15.12-18.24%) polypeptides of glycinin was registered. High content of a-subunit of P-conlycinin was determined (11.49-8.99%). The presence of Bowman-Birk TI as well as lypoxigenase, was not registered in any of protein isolates.

Cilj ovog rada bio je da se ispita uticaj nadpritiska 0,5 bara, radne temperature 96°C u trajanju od 5,10 i 15 minuta u autoklavu na promene polipeptidne strukture dobijenih proteinskih Izolata iz lomljenog sojinog zrna. Potvrđena je termostabilnost molekulaglicinina (47,14-53,08%), i manja stabilnost B-konglicinina (15,31-25,45%). Denzitomelrijska analiza SDS-elektroforegrama ukazuje na izraženu termostabilnost kiselih A1,2,4(27,50-26,31%) i baznih B1,2,3,4(18,24-15,12%) polipeptlda glicinina. Sadržaj a-polipeptida fikonglicinina pokazuje linearnu zavisnost od trajanja primenjenih tretmana (10,92-8,99%). Nakon ovih tretmana zapažena je smanjena tripsininhibitorska aktivnost (TIA), pri čemu je nosilac TIA Kunitz-ov TI (5,00-8,80%), dok je Bowman-Birk-ov inhibitor registrovan samo kod izolata iz netretiranog lomljenog sojinog zrna (3,92%).