Preparation and in Vitro Digestive Analysis of Casein-Derived Peptide-Zinc Chelates

In this study, casein peptides were obtained by alcalase hydrolyzation and Lactobacilus fermentation to prepare the casein peptide-zinc chelates, which are a kind of efficient and well-absorbed zinc supplement. The structure of casein peptide-zinc chelates was characterized by spectroscopic instruments. The digestive stability and safety were also assayed using in vitro digestive model and Caco-2 cell experiment. The results indicated that the optimal conditions for preparing casein peptides were as follows: Volume of alcalase was 0.3% (w/v), pH of reaction system was 9.0, Lactobacilus fermentation time was 12 h. Under this condition, the peptide content was 142.39±0.95 mg/g, and the zinc chelation rate was 31.41%±0.97%. The chelation with zinc destroyed the structure of casein peptides leading to a loose surface structure. Spectroscopic analysis showed that Zn2+ can bind to the reactive groups on casein peptides, with the chelating sites being carboxyl oxygen, hydroxyl oxygen and amino groups. The results of in vitro digestion showed that casein peptide-zinc chelates possessed better solubility than that of zinc sulfate. After gastrointestinal digestion, the DPPH and ABTS+ scavenging ability of casein peptide-zinc chelates increased by 26.19%±3.30% and 71.96%±7.06%, respectively. However, the ferric ion reducing power of the casein peptide-zinc chelates decreased by 36.26%±2.80%. At the same time, the β-turn and random coil content of the casein peptide-zinc chelate decreases during digestion, the β-sheet structure increases and Zn2+ play a role in maintaining the peptide structure. Furthermore, the cytotoxicity test indicated that casein peptide-zinc chelates gastrointestinal digest were toxic to Caco-2 cells when the concentration exceeded 0.4 mg/mL. Finally, 15 and 13 dairy-derived peptides were identified from casein hydrolysate and casein peptide-zinc chelates, respectively, using mass spectrometry. These results will provide scientific evidence for the development and application of efficient casein peptide-zinc chelates

Peptidomics approaches to the discovery and ACE inhibitory effect of casein peptides derived from fermented bovine milk by kefir grains

IntroductionKefir grains with efficient proteolytic system is an excellent starter culture for the production of bioactive peptides and milk products. This study explores the casein peptides derived from fermented bovine milk by kefir grains using the peptidomics approaches. The angiotensin converting enzyme (ACE) inhibitory activity of these peptides were also investigated.MethodsAfter fermentation, peptidomics based on the LC-MS/MS was used to investigate the dynamic profile and the structure specificity of generated peptides. The ACE inhibitory activity of peptides was determined by measuring the amount of hippuric acid (HA) by a spectrophotometer at 228 nm.ResultsThe results indicated that the cell envelope proteinases (CEPs) were the PI-/PIII-type. A total of 122 peptides were identified. The β-casein was preferentially hydrolyzed by kefir grains, and the main hydrolysis regions were f57-93, f132-160 and f192-209. The αs1-, and κ-casein were also hydrolyzed by a weaker degree. In the process of fermentation, the accumulated peptides increased with the fermentation time. The fermentation products exhibited ACE inhibitory activity, and this bioactivity remained 63% after simulated gastrointestinal (GI) digestion in vitro. Additionally, 14 Pro-containing peptides with ACE inhibitory activity were also identified.ConclusionThese results provide new insights and evidence to investigate the bioactive milk peptides generated by kefir grains fermentation, as well as a reference for the development of functional foods

Experimental Implementation of the Quantum Random-Walk Algorithm

The quantum random walk is a possible approach to construct new quantum algorithms. Several groups have investigated the quantum random walk and experimental schemes were proposed. In this paper we present the experimental implementation of the quantum random walk algorithm on a nuclear magnetic resonance quantum computer. We observe that the quantum walk is in sharp contrast to its classical counterpart. In particular, the properties of the quantum walk strongly depends on the quantum entanglement.Comment: 5 pages, 4 figures, published versio

The histone deacetylase inhibitor tubacin mitigates endothelial dysfunction by up-regulating the expression of endothelial nitric oxide synthase.

Endothelial nitric oxide (NO) synthase (eNOS) plays a critical role in the maintenance of blood vessel homeostasis. Recent findings suggest that cytoskeletal dynamics play an essential role in regulating eNOS expression and activation. Here, we sought to test whether modulation of cytoskeletal dynamics through pharmacological regulation of histone deacetylase 6 (HDAC6)-mediated tubulin deacetylation affects eNOS expression and endothelial function in vitro and in vivo.Wefound that tubulin acetylation inducer (tubacin), a compound that appears to selectively inhibit HDAC6 activity, dramatically increased eNOS expression in several different endothelial cell lines, as determined by both immunoblotting and NO production assays. Mechanistically, we found that these effects were not mediated by tubacin\u27s inhibitory effect on HDAC6 activity, but rather were due to its ability to stabilize eNOS mRNA transcripts. Consistent with these findings, tubacin also inhibited proinflammatory cytokine-induced degradation of eNOS transcripts and impairment of endothelium-dependent relaxation in the mouse aorta. Furthermore, we found that tubacin-induced up-regulation in eNOS expression in vivo is associated with improved endothelial function in diabetic db/db mice and with a marked attenuation of ischemic brain injury in a murine stroke model. Our findings indicate that tubacin exhibits potent eNOS-inducing effects and suggest that this compound might be useful for the prevention or management of endothelial dysfunction-associated cardiovascular diseases. © 2019 Chen et al

The majority coloring of the join and Cartesian product of some digraph

A majority coloring of a digraph is a vertex coloring such that for every vertex, the number of vertices with the same color in the out-neighborhood does not exceed half of its out-degree. Kreutzer, Oum, Seymour and van der Zyper proved that every digraph is majority 4-colorable and conjecture that every digraph has a majority 3-coloring. This paper mainly studies the majority coloring of the joint and Cartesian product of some special digraphs and proved the conjecture is true for the join graph and the Cartesian product. According to the influence of the number of vertices in digraph, we prove the majority coloring of the joint and Cartesian product of some digraph

The Effect of Molybdenum Fertilizer on the Growth of Grass–Legume Mixtures Related to Symbiotic Rhizobium

Molybdenum (Mo) is required by the enzymes involved in many metabolic processes related to plant growth and development. However, the effects of Mo addition on plant growth and beneficial microorganisms in mixed grasslands are unclear. We conducted a greenhouse experiment to examine the effects of different Mo addition levels (10 and 20 mg Mo kg−1 soil in the form of Na2MoO4) on the growth of perennial ryegrass–white clover in two low-Mo soils, as well as their symbiotic microorganisms. Our results showed that the addition of Mo had a significant impact on plant growth in limestone soil but not in yellow loam soil (p −1 significantly increased the plant community shoot and root biomass (p −1. The shoot nitrogen and phosphorus content in both soil types was unaffected by the Mo addition (p > 0.05), whereas the 10 mg Mo kg−1 addition significantly increased the shoot nitrogen and phosphorus uptake in limestone soil (p < 0.05). This increase in plant community productivity was primarily due to the increased growth of both species, caused by the enhanced activation of the symbiotic rhizobium. We conclude that Mo supply may promote N utilization and uptake in mixed grassland by increasing the activity of symbiotic rhizobium, resulting in a higher yield of mixed grassland, which is critical for sustainable agricultural development in low-Mo soils

Investment Style Drift Frequency and Fund Performance：Evidences from Open-Ended Funds

肖继辉(暨南大学管理学院)；周玉娟(暨南大学管理学院) 。【中文摘要】本文选取2008年7月之前成立的161只偏股型基金，借助Volkman五因素模型对样本基金的实际投资风格进行识别，并对基金在一年期和两年期时间窗口的漂移次数进行统计。采用Poisson回归系统性地检验了基金历史业绩与风格漂移频率之间的关系，并采用OLS回归检验基金风格漂移频率对基金未来业绩的影响。本文实证结果表明：基金历史业绩对本期风格漂移频率有负向影响； 而基金本期的风格漂移频率对基金未来期间业绩有正向影响。 【Abstract】We first use the Volkman five-factor model to identify the actual investment styles for a sample of 161 open-ended funds from which set up before July 2008. Then we examine the relation between the funds’ previous performance and their style drift frequencies in the following periods and the relation between the funds’ style drift frequencies and their future performance. Overall, we find that the previous performance has a negative effect on the style drift frequency and the style drift frequency has a positive effect on the future performance.本文系广东省自然科学基金项目“基金管理结构对投资行为、激励机制的影响机理及效应研究”（2014A030313372)，教育部人文社会科学基金“开放式基金锦标赛作用机理研究：理论拓展与经验证据”（2015YA630073）的阶段性成果