Enthalpic Relaxation of Vital and Protease-Treated Wheat Gluten

Commercially available vital wheat gluten was purified with α-amylase and treated with protease in a one-step process. The supernatant of the protease-treated gluten was freeze dried, quench cooled, and aged for 2 weeks and analyzed using differential scanning calorimetry, sodium dodecyl sulfate poly-acrylamide gel electrophoresis, reverse phase high performance liquid chromatography, size exclusion high performance liquid chromatography, capillary zone electrophoresis, and dynamic mechanical analysis. The differential scanning calorimetry profile of the aged (un-purified or un-modified) gluten sample exhibited enthalpic relaxation beneath its glass transition (Tg) indicating molecular relaxation. Samples treated with 0.006 g protease/g gluten showed Tg at 49.11°C with ΔCp = 0.12 (J/°C g). Higher protease levels and longer aging time caused high Tg temperature, ΔCp, and ΔH of enthalpic relaxation. The size exclusion high performance liquid chromatography profile of the protease-treated gluten clearly showed differences in molecular size between the supernatant and the precipitate, while reverse phase high performance liquid chromatography profiles signified more hydrophilic gluten molecules than the control. The small difference in gluten molecular size after protease treatments (0.024 g protease versus 0.032 g) appeared to have a significant effect on the enthalpic relaxation, where the two treatments showed different degrees of enthalpic relation. The capillary zone electrophoresis data confirmed the insignificant difference between 0.024 and 0.032 g protease/g gluten regarding the size to charge ratio. The molecular interactions for protease-treated gluten were much weaker than vital gluten, as indicated by much weaker network and sensitivity to temperature, especially above Tg. The weaker network was evidenced by higher G″ versus G′, which explained the fluid like behavior of the protease-treated gluten.     

两种蛋白酶水解大豆分离蛋白的特性研究

使用碱性蛋白酶Alcalase2.4L(EC3.4.21.62)和中性蛋白酶Protease N(IUB3.4.24.28)在间歇式反应器和酶膜反应器中水解大豆分离蛋白(SPI),并对其水解特性进行了研究。结果表明:Protease N具有较高的蛋白酶水解活力,最适作用温度低并且稳定性好,水解过程中易受产物抑制;两种酶水解产物的相对分子质量均小于10000Da,游离氨基酸含量较低;Protease N更适合用于酶膜反应器中水解SPI。      

Effect of protease inhibitors from Adenanthera pavonia on the biochemical and microbiological quality of fishes

Fishes were given dip treatment in protease inhibitors extracted from Indian red wood seeds (Adenanthera pavonia) and their microbiological and biochemical characters were examined during storage at refrigerator temperatures. The results suggest that protease inhibitors bring about qualitative and quantitative changes in the microflora. Production of trimethylamine (TMA) and volatile bases appeared to be suppressed in the treated fishes. Incorporation of protease inhibitors in broth suppressed such activities as reduction of trimethylamine oxide, production of H₂ S and hydrolysis of gelatin in a significant proportion of bacterial cultures.     

UTILIZATION OF PRETREATED MOLASSES FOR SERINE ALKALINE PROTEASE PRODUCTION WITH RECOMBINANT BACILLUS SPECIES

Recombinant Bacillus amyloliquefaciens, Bacillus cereus, Bacillus subtilis , and Bacillus licheniformis were used for the production of serine alkaline protease (SAP) utilizing chemically and/or physically pretreated molasses. The highest enzyme activity was obtained with r- Bacillus subtilis , with the complex medium involving physically treated molasses having 20 kg m -3 initial sucrose concentration in small-scale, agitation- and heating rate-controlled bioreactors at t=63 h. Effects of oxygen transfer were investigated in 3.5 dm 3 laboratory bioreactors under two different agitation rates with r- B. subtilis . Increase in the oxygen transfer rate increased the observed activity and caused the cultivation time of maximum activity shift to the earlier stages of the fermentation. At Q/V=0.5 vvm and N=750 min -1 , SAP activity reached 2250U cm -3 at t=36 h.     

Understanding fibroblast activation protein (FAP): Substrates,activities, expression and targeting for cancer therapy

Fibroblast activation protein (FAP) is best known for its heightened expression in tumour stroma. This atypical serine protease has both dipeptidyl peptidase and endopeptidase activities, cleaving substrates at a post-proline bond. FAP expression is difficult to detect in non-diseased adult organs, but is greatly upregulated in sites of tissue remodelling, which include liver fibrosis, lung fibrosis, atherosclerosis, arthritis, tumours and embryonic tissues. Due to its restricted expression pattern and dual enzymatic activities, FAP is emerging as a unique therapeutic target. However, methods to exploit and target this protease are advancing more rapidly than knowledge of the fundamental biology of FAP. This review highlights this imbalance, emphasising the need to better define the substrate repertoire and expression patterns of FAP to elucidate its role in biological and pathological processes.     

蛋白酶在羊毛丝光防毡缩整理中的应用研究

研究了蛋白酶Argaenzyme STL在羊毛丝光防毡缩加工中的应用，探讨了不同的前处理助剂、酶处理工艺以及稳定剂对酶处理效果的影响，并比较了酶处理前后羊毛物化性能的变化。     

Amino acid profile and enhancement of the enzymatic hydrolysis of fermented shrimp carotenoproteins

Amino acid profiles of carotenoproteins extracted from fermented and non-fermented shrimp waste were analysed. Fermented carotenoproteins were hydrolysed with a protease and a combination of a protease and a lipase. Essential amino acids in fermented and non-fermented carotenoproteins were 49% and 47%, respectively, with respect to total amino acids. The highest carotenoprotein hydrolysis (900 and 66 mg/g soluble protein and total carotenoids, respectively) was obtained by a combination of 15 proteolytic units together with 10 lipolytic units. The most efficient treatment using only protease was obtained with 15 proteolytic units (852 and 48 mg/g of soluble protein and total carotenoids, respectively). A relatively protein-free form of astaxanthin derived from shrimp waste carotenoproteins may be of interest for applications in salmon culture, and in natural health products and cosmetics. Furthermore, fermented carotenoproteins could be used in human and animal diets due to their high essential amino acids concentration.     

Effects of oxidase and protease treatments on the breadmaking functionality of a range of gluten-free flours

In this study, the application of glucose oxidase and protease commercial preparations was investigated in order to evaluate their impact on the breadmaking performance of four different gluten-free flours (buckwheat, corn, sorghum and teff). Bread formulas were developed without addition of hydrocolloids in order to avoid synergistic effects. Glucose oxidase improved corn (CR) and sorghum (SG) bread quality by increasing specific volume (P < 0.05) and reducing collapsing at the top. The improvements could be related to protein polymerization which resulted in enhanced continuity of the protein phase and elastic-like behavior of CR and SG batters. No significant effects were detected on buckwheat (BW) and teff breads. On the other hand, protease treatment had detrimental effects on the textural quality of BW and SG breads. The effects were related to protein degradation resulting in increased liquid-like behaviour of BW and SG batters. Overall, the results of this study suggest that protein polymerisation can improve the breadmaking performance of gluten-free flours by enhancing elastic-like behaviour of batters. However, the protein source is a key element determining the impact of the enzymes. In the absence of hydrocolloids, protein structures are important to ensure the textural quality of these types of breads.