Streamlined Efficient Synthesis and Antioxidant Activity of γ-[Glutamyl](n≥1)-tryptophan Peptides by Glutaminase from Bacillus amyloliquefaciens.

As a group of naturally occurring peptides in various foods, γ-glutamyl peptides possess a unique Kokumi taste and health benefits. However, few studies have focused on the functionality of γ-glutamyl peptides. In this study, the γ-[glutamyl] (n=1, 2, 3)-tryptophan peptides were synthesized from a solution of glutamine (Gln) and tryptophan (Trp) employing L-glutaminase from Bacillus amyloliquefaciens. Four different γ-glutamyl peptides were identified from the reaction mixture by UPLC-Q-TOF-MS/MS. Under optimal conditions of pH 10, 37 °C, 3 h, 0.1 mol/L Gln: 0.1 mol/L Trp = 1:3, and glutaminase at 0.1% (m/v), the yields of γ-l-glutamyl-l-tryptophan (γ-EW), γ-l-glutamyl-γ-l-glutamyl-l-tryptophan (γ-EEW) and γ-l-glutamyl-γ-l-glutamyl-γ-l-glutamyl-l-tryptophan (γ-EEEW) were 51.02%, 26.12% and 1.91% respectively. The antioxidant properties of the reaction mixture and the two peptides (γ-EW, γ-EEW) identified from the reaction media were further compared. Results showed that γ-EW exhibited the highest DPPH•, ABTS•+ and O2•--scavenging activity (EC50 = 0.2999 mg/mL, 67.6597 µg/mL and 5.99 mg/mL, respectively) and reducing power (EC50 = 4.61 mg/mL), while γ-EEW demonstrated the highest iron-chelating activity (76.22%). Thus, the synthesized mixture may be used as a potential source of antioxidant peptides for food and nutraceutical applications.

Novel iron-chelating peptide from egg yolk: Preparation, characterization, and iron transportation.

In this work, an egg yolk protein hydrolysate (EYPH) with a high iron-chelating ability (87.32%) was prepared. The fractionation using 60% (v/v) ethanol concentration (E3 fraction) led to the efficiently accumulating the iron-chelating peptides in EYPH. The characterization results showed that iron mainly chelated with carboxyl, amino and phosphate groups of peptides. From E3 fraction, six iron-chelating peptides with MW ranging from 1372.36 to 2937.04 Da were identified and a hypothesized molecular model of DDSSSpSpSpSpSpSVLSK-Fe was simulated. In vitro stability determination showed that E3-Fe chelate owned a good heat, alkalinity and digestion tolerance, but a relatively bad acid tolerance. Finally, iron transport analysis showed that iron in the E3-Fe would be absorbed in caco-2 cell membrane more effectively than that of iron salts, indicating that it was possible to apply the E3-Fe complex as iron supplements.

Donkey Industry in China: Current Aspects, Suggestions and Future Challenges.

Donkey domestication has been essential to human culture and development and has played an important role in economic and social life in human history. China is one of the largest donkey breeders worldwide; donkey farming for meat, milk and hide production is becoming an important industry in rural China as it provides income to the rural livelihoods of many people. Currently, the donkey industry in China is small and relatively young, but it is growing fast. The industry is not adequately exploited economically, which means that it requires the diminution of its role in the traditional activities of rural households and a reorientation towards a more profitable industry. Given the growing importance of the donkey industry in rural China, this paper aims to outline the current situations of the donkey industry in China in terms of animal stock, breeds and distribution, donkey products, suggestions and future challenges to the development of the donkey industry.