Improved extraction of disulphide‐rich bioactive proteins from soya hulls: characterisation of a novel aspartic proteinase

Abstract

Summary Soya hull, an underutilised coproduct of soya processing, was investigated as a source of disulphide‐rich bioactive proteins. A Viscozyme L‐assisted extraction method was developed to improve the yield of extracted proteins. The extracted proteins were identified by MALDI TOF–TOF MS, and the most abundant disulphide‐rich protein among identified proteins was purified and the enzymatic properties were evaluated. The results indicated that the Viscozyme L‐assisted extraction method extracted significantly (P < 0.05) more proteins (39.01%) than did the aqueous method (4.52%). The yield of the purified aspartic proteinase nepenthesin‐1‐like [Glycine max] (GmAPN1K) (the most abundant disulphide‐rich protein) is 570 mg Kg−1. The specific activity of GmAPN1K was 62.1 U mg−1 at pH 3.0 and 37 °C. The enzyme was optimally active at pH 3.0 and 55 °C. It was stable within pH range 3.0–10.0 and up to 55 °C, respectively, and was specifically inhibited by pepstatin A.

Antitumor activity and ability to prevent acrylamide formation in fried foods of asparaginase from soybean root nodules

“…The clear supernatant was collected, dialyzed, and freeze‐dried, the lyophilized powder was designated as the crude protein extract. The protein content of the crude protein was determined using the micro‐Kjeldahl method (Liu, Cheng, Liu, Ma, & Yang, ). The crude protein extract was analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS–PAGE) (Laemmli, ).…”