Studies On Preparation Of Corn Peptides Through Double Enzyme Immobilization Technique

Multipoint connection could be formed between enzyme and carrier material through enzyme immobilization technology, which could effectively avoid the deformation and autolysis phenomenon and the stability of enzyme could be significantly improved. Double enzymes immobilized within composite carrier could not only make up for the lack of a single carrier but to improve the efficiency of enzymatic hydrolysis. For the purpose on preparation of active peptides through double proteases immobilization, improving the efficiency of enzymatic hydrolysis, the properties and applications of double proteases immobilized within alginate-chitosan(ACDP) and crosslinked enzyme aggregates(CLEAs) were studied.First of all, the preparation of active corn peptide(CPs) by double enzymes immobilized within composite carrier was studied. Based on sodium alginate-chitosan composite carrier, alkaline protease and trypsin were immobilized and used with zein as the substrate to prepare active CPs. The traditional method and the experimental method for the degradation of zein effect were comparatively studied. It was found that the zein degradation efficiency with the experimental method was higher than that of the traditional methods. The immobilization conditions for ACDP were optimized at the same time. Five different CPs fractions with different molecular weight distributions(F1: > 6 kDa, F2:4 kDa-6 kDa, F3: < the CPs-4 kDa, CPs-1, CPs-2) were obtained from zein hydrolysate. The antioxidant activity and antihypertensive activity analysis of five CPs fractions showed that better activity were obtained with CPs owning to the smaller range of molecular weight distribution. The IC50 on antioxidant activity of CPs-1 and CPs-2 were 0.47 and 0.23 mg/m L, respectively; CPs-2 had 79.34% inhibitory rate on ACEI in vitro,and the SBP of SHRs was declined with 44.6 mm Hg and DBP was declined with 10.2 mm Hg after 12 h of administration of CPs-2 at the dose of 10 mg/kg. Therefore, active CPs could be obtained through double enzymes immobilized within sodium alginate- chitosan composite carrier technique.Secondly, the crosslinked double-proteases aggregation was studied. Two kinds of protease, neutral protease and papain were precipitated by ethanol and further crosslinked by glutaraldehyde, then crosslinked neutral protease- papain aggregates(CLEAs) were obtained. The optimum factors were determined as follows: the best precipitant was ethanol, double enzyme/glutaraldehyde ratios was 1/5, the crosslinked time was 4 hours. The stability of obtained enzyme aggregates was higher than that of free protease. CLEAs was applicable to water soluble protein(soy bean, mung bean, adzuki bean and mung bean protein) and alcohol soluble corn protein, and its degree of hydrolysis of the protein was higher(7.79%、12.01%、10.22%、9.04% and 5.18%, respectively) than those of free enzyme hydrolysis degree(7.25%、7.53%、6.18%、7.17% and 1.89%, respectively),(P<0.05). Thus, immobilized double proteases with good stability could be obtained through the use of enzyme aggregates, which could laid a foundation for subsequent application of immobilized enzyme.