Abstract:

Neutral protease AS1.398 was used to hydrolyze peanut protein to produce polypeptides. The effects of pH, enzyme dosage, hydrolysis time and temperature on degree of hydrolysis were investigated through single factor tests respectively, and these factors were optimized through response surface methodology (RSM) that was designed based on Box-Behnken central combination. The optimum hydrolysis conditions are as follows: pH 6.7, enzyme dosage (ratio of enzyme to substrate) 6500 U/g, hydrolysis temperature 50 ℃ and time 2.5 h. The hydrolysates of peanut were ultrafiltrated with 5-kD or 3-kD hollow fiber ultrafiltration membrane, and the retentates of 5-kD and 3-kD hollow fiber ultrafiltration membrane was collected respectively and then purified through Sephadex G-25 column chromatography with 10% ethanol solution as eluent. Chromatogram showed that the retentate of 5-kD hollow fiber ultrafiltration membrane is composed of two fractions, whose molecular weights are about 6.5 kD and 2 kD determined using SDS-PAGE method, respectively.

Key words: peanut polypeptides, preparation, isolation, purification