Potential of Thermolysin-like Protease A69 in Preparation of Bovine Collagen Peptides with Moisture-Retention Ability and Antioxidative Activity

Bovine bone is rich in collagen and is a good material for collagen peptide preparation. Although thermolysin-like proteases (TLPs) have been applied in different fields, the potential of TLPs in preparing bioactive collagen peptides has rarely been evaluated. Here, we characterized a thermophilic TLP, A69, from a hydrothermal bacterium Anoxybacillus caldiproteolyticus 1A02591, and evaluated its potential in preparing bioactive collagen peptides. A69 showed the highest activity at 60 °C and pH 7.0. We optimized the conditions for bovine bone collagen hydrolysis and set up a process with high hydrolysis efficiency (99.4%) to prepare bovine bone collagen peptides, in which bovine bone collagen was hydrolyzed at 60 °C for 2 h with an enzyme–substrate ratio of 25 U/g. The hydrolysate contained 96.5% peptides that have a broad molecular weight distribution below 10000 Da. The hydrolysate showed good moisture-retention ability and a high hydroxyl radical (•OH) scavenging ratio of 73.2%, suggesting that the prepared collagen peptides have good antioxidative activity. Altogether, these results indicate that the thermophilic TLP A69 has promising potential in the preparation of bioactive collagen peptides, which may have potentials in cosmetics, food and pharmaceutical industries. This study lays a foundation for the high-valued utilization of bovine bone collagen.

A synthesis review on atmospheric wet deposition of particulate elements: scavenging ratios, solubility and flux measurements

Atmospheric dry and wet deposition of particulate matter controls its lifetime in air and contributes to the environmental burden of toxic pollutants, and thus has important implications on human and ecosystem health. This synthesis review focused on atmospheric wet deposition of particulate elements and analyzed their scavenging ratios (i.e. concentration in precipitation to that in ambient air), solubility and wet deposition flux measurements based on published studies in literature, aiming to gather updated knowledge that can be used for modeling their wet deposition. Our analysis finds that scavenging ratios of a specific element have a narrow range. Overall, elemental scavenging ratios for snow are ~3 times higher than those for rain. Elements that are bound to coarse (PM2.5-10) particles have larger scavenging ratios than those bound to fine (PM2.5) particles except for Fe and Si. Solubility of elements in rainwater range from 8% (Fe) to 94% (Ca). Solubility is moderately correlated with scavenging ratio possibly explaining the lower scavenging ratios of Fe and Si compared to other elements with similar fine fraction. Data collected from North America, Europe, the Middle East, and Asia show that the wet fluxes of Al and Fe are orders of magnitude greater than those of routinely-monitored anthropogenic elements (Zn, Pb, Cu, Ni, Cd, Cr). Wet deposition fluxes of particulate elements in the Middle East exceed those in other regions, likely due to regional transport of dust and soil resuspension. Fluxes from all regions are a factor of 2-3 greater in industrialized and urban locations than rural and remote locations because of industrial, vehicular and soil and mineral dust emissions. Dry deposition fluxes are usually greater than wet deposition fluxes although to varying degrees according to co-located measurements. Based on the relationships between scavenging ratio and elemental PM2.5 fraction under rain and snow conditions, we derived regression equations for estimating scavenging ratios of particulate elements whose measurements are limited. Such knowledge and data improves the quantification of atmospheric deposition fluxes for an expanded list of metals and metalloids and the understanding of pathways contributing to ecological risk.

Scavenging of atmospheric particulates by snow in Changji, China

<p>Changji is an arid city in the north west of China which suffers from severe air pollution due to increasing vehicle use and heating with coal. Samples (TSP, PM10, PM5, PM2.5) were collected before and after several snow events, for revealing the snow scavenging effect and influencing mechanisms. The result indicated that the snow scavenging effect was obvious. The highest snow scavenging quantity and scavenging ratio is TSP, followed by PM10, PM5 and PM2.5. Snow scavenging quantity was dependent on the particulate diameter. Snow intensity, drying time and amount of snow influenced scavenging ratio, and snow intensity is the key influencing factor. Scavenging ratio increases with the increase of snow intensity. Higher snow intensity can reduce the selective scavenging of particulate diameters, the scavenging ratio of different particulate diameter will get close to each other. The lower snow intensity was, the higher selectivity was. Light snow will scavenge large particles obviously, but little for small particle.</p>

Elemental carbon in snow at Changbai Mountain, northeastern China: concentrations, scavenging ratios, and dry deposition velocities

Light-absorbing aerosol – particularly elemental carbon (EC) – while mixed with snow and ice is an important climate driver from the enhanced absorption of solar radiation. Currently, considerable efforts are being made to estimate its radiative forcing on a global scale, but several uncertainties remain, particularly those regarding its deposition processes. In this study, concurrent measurements of EC in air and snow are performed for three years (2009–2012) at Changbai station, northeastern China. The scavenging ratio and the wet- and dry-deposition fluxes of EC over the snow surface are estimated. The mean EC concentration in the surface snow is 1000 ± 1500 ng g−1, ranging from 7 to 7640 ng g−1. The mean value of the scavenging ratio of EC by snow is 140 ± 100, with a median value of 150, which is smaller than that reported in Arctic areas. A non-rimed snow process is a significant factor in interpreting differences with Arctic areas. Wet-deposition fluxes of EC are estimated to be 0.47 ± 0.37 μg cm−2 month−1 on average over the three snow seasons studied. Dry deposition is more than five times higher, with an average of 2.65 ± 1.93 μg cm−2 month−1; however, only winter period estimation is possible (December–February). During winter in Changbai, 87% of EC in snow is estimated to be due to dry deposition, with a mean dry deposition velocity of 6.44 × 10−3 m s−1 and median of 8.14 × 10−3 m s−1. Finally, the calculation of the radiative effect shows that 500 ng g−1 of dry-deposited EC to a snow surface absorbs three times more incoming solar energy than the same mass mixed in the snow through wet deposition. Deposition processes of an EC-containing snow surface are, therefore, crucial to estimate its radiative forcing better, particularly in northeastern China, where local emission strongly influences the level and gradient of EC in the snowpack, and snow-covered areas are cold and dry due to the atmospheric general circulation. Furthermore, this study builds on the knowledge to characterize the conditions in the snow-laden Chinese rural areas better as well as to constrain transport of EC to the Arctic better.

Influence of pH on Hydroxyl Radical Scavenging Ratio by Gingerol

In this paper, the work was mainly studying influence of pH on Fenton reaction and gingerol scavenging hydroxyl radical. The antioxidant activity of gingerol was characterized by the scavenging hydroxyl ratio and scavenging hydroxyl ratio was analyzed by the spectrophotometry. Hydroxyl radical was produced by Fenton reaction. In the experiment pH and buffer solution have influence on the scavenging hydroxyl radical and Fenton reaction. Gingerol exhibits a strong scavenging radical activity for hydroxyl radical (OH.). The scavenging hydroxyl radical of different extractions of ginger oleoresin is different.

Elemental carbon in snow at Changbai Mountain, Northeastern China: concentrations, scavenging ratios and dry deposition velocities

Light absorbing aerosol, in particular elemental carbon (EC), in snow and ice enhance absorption of solar radiation, reduce the albedo, and is an important climate driver. In this study, measurements of EC concentration in air and snow are performed concurrently at Changbai Station, Northeastern China, from 2009 to 2012. The mean EC concentration for surface snow is 987 &amp;pm; 1510 ng g−1 with a range of 7 to 7636 ng g−1. EC levels in surface snow around (about 50 km) Changbai Mountain are lower than those collected on the same day at Changbai station, and decrease with distance from Changbai station, indicating that EC load in snow around Changbai Mountain is influenced by local source emissions. Scavenging ratios of EC by snow are calculated through comparing the concentrations of EC in fresh snow with those in air. The upper-limit of mean scavenging ratio is 137.4 &amp;pm; 99.7 with median 149.4, which is smaller than those reported from Arctic areas. The non-rimed snow process may be one of significant factors for interpreting the difference of scavenging ratio in this area with the Arctic areas. Finally, wet and dry depositional fluxes of EC have been estimated, and the upper-limit of EC wet deposition flux is 0.46 &amp;pm; 0.38 μg cm−2 month−1 during the three consecutive snow season, and 1.32 &amp;pm; 0.95 μg cm−2 month−1 for dry deposition flux from December to February during study period. During these three years, 77% of EC in snow is attributed to the dry deposition, indicating that dry deposition processes play a major role for EC load in snow in the area of Changbai, Northeastern China. Based on the dry deposition fluxes of EC and hourly black carbon (BC) concentrations in air, the estimated mean dry deposition velocity is 2.81 × 10−3 m s−1 with the mean median of 3.15 × 10−3 m s−1. These preliminary estimates for the scavenging ratio and dry deposition velocity of EC on snow surface will be beneficial for numerical models, and improve simulations of EC transport, fate and radiative forcing in order to ultimately make better climate prediction.

Process Optimization and Composition Analysis of Antioxidant Enzymatic Hydrolysate from Squid By-Products by Papain

In order to evaluate the high-value application of squid by-products yielded hydrolysate, the process of preparation and purification technology, chemical composition and in vitro antioxidant activity of the hydrolysate were investigated. The optimal conditions of papain hydrolysis were obtained by single-factor experiments and orthogonal test with the DPPH• scavenging ratio as index, amino acid composition was analysed by automatic amino acid analyzer, the hydrolysate was isolated with a Sephadex G-25 column. Based on single-factor experiments, the hydrolysate with the DPPH• scavenging ratio being 53.96 % was gained under the optimal condition of enzymolysis temperature of 45 °C, enzymolysis time of 3 h, total enzyme dose of 1.2 %, and the pH value of 7. The protein content of the hydrolysate reached up to 17.53 %, and the essential amino acids were accounted for 51.06 % of total amino acids. The largest content amino acid was glutamic acid, which accounted for 10.74 % of total amino acids. Compared with the amino acid profiles recommended by FAO/WHO, the quality of the protein hydrolysate was high, as it was rich in essential amino acids, including isoleucine, leucine, lysine, methionine and cystine, threonine, tryptophan, and valine, which covered 88 %-100 % of the FAO/WHO recommended. The hydrolysate was divided into three fractions (F1-F3) using a Sephadex G-25 column, the F1 possessed the highest antioxidation activity with the reducing power, •OH and DPPH• scavenging ratio being 0.236, 18.13 % and 63.85 % at the concentration of 5 mg/mL. Compared with the retention time of the reduced glutathione chromatomap, the relative molecular mass of F1 was higher than 307, F2 and F3 was lower than 307. The result revealed that the protein hydrolysate from squid by-products by papain had strongly antioxidant capacity in vitro and high nutrition, and this finding provided a new way of advanced exploitation of squid scrap resources.