BACKGROUND The salt tolerance of proteases secreted by Aspergillus oryzae 3.042 closely relates to the utilization of raw materials and the quality of soy sauce. However, little is known about the salt‐tolerant proteases and their salt‐tolerant mechanisms. RESULTS In this study, we isolated and identified a salt‐tolerant alkaline protease (AP, approximately 29 kDa) produced by A. oryzae 3.042. It was considered as a metal‐ion‐independent serine protease. The optimum and stable pH values were both pH 9.0 and the optimum temperature was 40 °C. Over 20% relative activity of AP remained in the presence of 3.0 mol L−1 NaCl after 7 days, but its Km and Vmax were only mildly influenced by the presence of 3.0 mol L−1 NaCl, indicating its outstanding salt tolerance. Furthermore, AP was more stable than non‐salt‐tolerant protease at high salinity. The salt‐tolerant mechanisms of AP could be due to more salt bridges, higher proportion of ordered secondary structures and stronger hydrophobic amino acid residues in the interior. CONCLUSIONS The above results are vital for maintaining, activating and/or modulating the activity of AP in high‐salt environments. They would also provide theoretical guidance for the modification of AP and the engineering of A. oryzae 3.042 so as to secrete more AP. © 2018 Society of Chemical Industry

Cover: The image shows electrospun fibers based on poly(lactic acid)/polyaniline blends with diameters from 90 to 1000 nm. The structural characteristics of the fibers are compared to cast films by scanning electron microscopy, small‐angle X‐ray scattering, differential scanning calorimetry, and atomic force microscopy. It is found that the electrospinning process governs the crystal structure of the fibers and strongly affects blending properties. Further details can be found in the article by Paulo H. S. Picciani,* Eliton S. Medeiros, Zhongli Pan, Delilah F. Wood, William J. Orts, Luiz H. C. Mattoso, and Bluma G. Soares .

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BACKGROUND The main objective of this study was to evaluate the safety and antihypertensive activity of rapeseed peptides and to investigate their potential synergy with captopril. RESULTS The peptides were nontoxic with the maximum tolerated dose exceeding 25 g kg−1 BW d−1 for mice and they had angiotensin converting enzyme (ACE) inhibitory activity with IC50 value of 1.27 mg mL−1. Rapeseed peptides did not have a synergistic effect with captopril on inhibiting ACE activity in simulated digestion tests in vitro. But in vivo they could synergistically augment the amplitude range of lowering blood pressure with captopril by approximately 9% and prolong the antihypertensive effect duration time by over 20% in antihypertension tests of spontaneously hypertensive rats. In addition, the inhibiting effect of rapeseed peptides on ACE activity was noticeable in some rat organs in vivo. Nevertheless, when compared to captopril group, the potential synergy of rapeseed peptides with captopril did not cause a further decrease in ACE activity in the organs but their synergy further improved levels of NO (12.7%) and endothelial nitric oxide synthase (74.1%) in rat serum. Further studies of some peptides identified from rapeseed peptides showed that some of the rapeseed peptides (Cys‐Leu, Val‐Ala‐Pro) could markedly increase contents of NO and endothelial nitric oxide synthase. CONCLUSIONS Rapeseed peptides have antihypertensive activity and they showed potential synergy with captopril in antihypertensive performance in vivo. The synergy was not from ACE inhibition but from other pathways, like improvement in endogenous vasodilator contents. © 2020 Society of Chemical Industry