Kinetic and thermodynamic analysis of ultra-high pressure and heat-induced denaturation of bovine serum albumin by surface plasmon resonance

Purpose: To undertake comparative kinetic and thermodynamic analyses of the interaction of bovine serum albumin (BSA) with IgG pre-treated with ultra-high pressure (UHP) and moderate heat.Methods: BSA solutions were processed at 100 – 600 MPa and 25 – 40 °C. We applied an optical biosensor based on surface plasmon resonance (SPR). The dissociation and association kinetics of antigen-antibody complexes were measured at different temperatures. By analyzing the resultant sensograms, the association rate constant (ka), dissociation rate constant (kd), equilibrium dissociation constant (KD), and thermodynamic parameters were calculated.Results: The equilibrium disassociation constant, KD, ranged from a low value of 3.15 × 10−7 M (0.1 MPa, 25 °C) to a high value of 66.42 × 10−7 M (600 MPa, 55 °C). Increase in pressure and temperature led to decrease in the affinity of BSA for IgG. Pressure levels above 300 MPa promoted interactions between breakage of disulfide bonds, and the unfolding and aggregation of BSA.Conclusions: These results show that the combination of UHP and moderate heat treatment cdecrease the allergenicity of BSA by changing their protein conformation.Keywords: Ultra - high pressure, Bovine serum albumin, Surface plasmon resonance, Kinetics, Thermodynamics, Allergen

Interplay between residual protease activity in commercial lactases and the subsequent digestibility of β-casein in a model system

One of the conventional ways to produce lactose-hydrolyzed (LH) milk is via the addition of commercial lactases into heat-treated milk in which lactose is hydrolyzed throughout storage. This post-hydrolysis method can induce proteolysis in milk proteins due to protease impurities remaining in commercial lactase preparations. In this work, the interplay between lactose hydrolysis, proteolysis, and glycation was studied in a model system of purified β-casein (β-CN), lactose, and lactases using peptidomic methods. With a lactase presence, the proteolysis of β-CN was found to be increased during storage. The protease side-activities mainly acted on the hydrophobic C-terminus of β-CN at Ala, Pro, Ile, Phe, Leu, Lys, Gln, and Tyr positions, resulting in the formation of peptides, some of which were N-terminal glycated or potentially bitter. The proteolysis in β-CN incubated with a lactase was shown to act as a kind of “pre-digestion”, thus increasing the subsequent in vitro digestibility of β-CN and drastically changing the peptide profiles of the in vitro digests. This model study provides a better understanding of how the residual proteases in commercial lactase preparations affect the quality and nutritional aspects of β-CN itself and could be related to its behavior in LH milk

Purified dietary red and white meat proteins show beneficial effects on growth and metabolism of young rats compared to casein and soy protein

This study compared the effects of casein, soy protein (SP), red (RMP) and white meat (WMP) proteins on growth and metabolism of young rats. Compared to casein, the ratio of daily feed intake to daily body weight gain of rats was not changed by meat protein but reduced by SP by 93.3% (P<0.05). Feeding RMP and WMP reduced the liver total cholesterol (TC) contents by 24.3% and 17.8% respectively (P<0.05). Only RMP increased plasma HDL-cholesterol concentrations (by 12.7%, P<0.05), whereas SP increased plasma triacylglycerol, TC and LDL-cholesterol concentrations by 23.7%, 19.5% and 61.5% respectively (P<0.05). Plasma essential and total amino acid concentrations were increased by WMP (by 18.8% and 12.4%, P<0.05) but reduced by SP (by 28.3 and 37.7%, P<0.05). Twenty five liver proteins were differentially expressed in response to different protein sources. Therefore, meat proteins were beneficial for growth and metabolism of young rats compared to casein and SP

A review of ant nests and their implications for architecture

This paper discusses the latest progress in research on ant nests and explores innovative scientific concepts associated with underground ant nests from the perspective of bionics. The methods used by scholars to study the structure of ant nests and the interaction between the structure itself and the individual ants are investigated. The structural characteristics of the ant nest, its internal environment and ventilation characteristics are discussed in detail. In addition, this paper presents an innovative project in which the effect of underground ant nests on soil geotechnical properties and the effect of calcined ant nest soil powder, from the perspective of civil engineering, are addressed. Practical examples of the application of the structural and inter-relational aspects of subterranean ant nests in the field of architectural bionics are also provided, from the perspectives of construction, morphology, function and material. This review attempts to integrate civil engineering, architecture and biology, enlighten architects and biologists on converging their thinking, provide new ideas regarding underground ant colony nests, and provide references for long-term human habitation

Redox Regulation in Cancer Stem Cells

Reactive oxygen species (ROS) and ROS-dependent (redox regulation) signaling pathways and transcriptional activities are thought to be critical in stem cell self-renewal and differentiation during growth and organogenesis. Aberrant ROS burst and dysregulation of those ROS-dependent cellular processes are strongly associated with human diseases including many cancers. ROS levels are elevated in cancer cells partially due to their higher metabolism rate. In the past 15 years, the concept of cancer stem cells (CSCs) has been gaining ground as the subpopulation of cancer cells with stem cell-like properties and characteristics have been identified in various cancers. CSCs possess low levels of ROS and are responsible for cancer recurrence after chemotherapy or radiotherapy. Unfortunately, how CSCs control ROS production and scavenging and how ROS-dependent signaling pathways contribute to CSCs function remain poorly understood. This review focuses on the role of redox balance, especially in ROS-dependent cellular processes in cancer stem cells (CSCs). We updated recent advances in our understanding of ROS generation and elimination in CSCs and their effects on CSC self-renewal and differentiation through modulating signaling pathways and transcriptional activities. The review concludes that targeting CSCs by manipulating ROS metabolism/dependent pathways may be an effective approach for improving cancer treatment

Ventilation simulation in an underground ant nest structure of Camponotus japonicus Mayr

Ants are ancient animals on the earth and are known as excellent architects in the animal kingdom. The structure and performance of their nests are full of remarkable mysteries. At present, there are only a limited number of studies on the ventilation performance of underground ant nest structures. In this study, the nests of Camponotus japonicus Mayr were collected manually, and a three-dimensional digital model of the ant nest structure was obtained by the method of industrial CT scanning. The ventilation performance of the Camponotus japonicus Mayr nest structure was numerically simulated using the finite element analysis software, FLUENT. By changing the air inlet and outlet of the nest, the pressure changes inside the nest and the trajectory of the air flow inside the nest could be calculated and analysed, in order to explore the ventilation characteristics of the underground nest structure during natural ventilation. It was found that the ventilation environment inside the nest was stable, and that the external air flow had little effect on the life of the ants inside the nest

Study on rock-breaking efficiency evaluation of TBM disc cutters based on Rostami prediction equations

As the main cutting tool of Tunnel Boring Machine (TBM) for rock-breaking, the rock-breaking efficiency of TBM disc cutters directly affects the TBM’s boring speed, which in turn affects the overall progress of the tunnelling project. Therefore, a simple and accurate evaluation method of the rock-breaking efficiency of TBM disc cutters is an essential prerequisite to improve the rock-breaking performance of TBM. In this paper, the classical force prediction equations of disc cutters were summarized and the applicability of each equation for the constant cross-section disc cutters was analyzed. The calculation equation of the specific energy per ring of TBM rock-breaking was derived based on the Rostami prediction equations and the specific energy theory for disc cutter rock-breaking. The specific energy per ring equation was verified through a practical engineering case. The results show that the maximum relative error of the effective thrust force and the effective torque of the cutter head based on the Rostami force prediction equations is 9.8%. The relative error of the specific energy per ring is 8.0%, which indicates that the prediction of the specific energy per ring equation can accurately reflect the rock-breaking efficiency of disc cutters. The derived equation of the specific energy per ring can not only simplify the rock-breaking efficiency evaluation of TBM disc cutters, but also serve as a valuable reference for practical engineering projects

Differences in Physicochemical and Nutritional Properties of Breast and Thigh Meat from Crossbred Chickens, Commercial Broilers, and Spent Hens

The objective of this study was to compare the physicochemical and nutritional properties of breast and thigh meat from commercial Chinese crossbred chickens (817 Crossbred chicken, 817C), imported commercial broilers (Arbor Acres broiler, AAB), and commercial spent hens (Hyline Brown, HLB). The crossbred chickens, commercial broilers and spent hens were slaughtered at their typical market ages of 45 d, 40 d, and 560 d, respectively. The results revealed that several different characteristic features for the three breeds. The meat of the 817C was darker than that of the other two genotypes. The 817C were also characterized by higher protein, lower intramuscular fat, and better texture attributes (cooking loss, pressing loss and Warner-Bratzler shear force [WBSF]) compared with AAB and HLB. The meat of the spent hens (i.e. HLB) was higher in WBSF and total collagen content than meat of the crossbred chickens and imported broilers. Furthermore, correlation analysis and principal component analysis revealed that there was a clear relationship among physicochemical properties of chicken meats. With regard to nutritional properties, it was found that 817C and HLB exhibited higher contents of essential amino acids and essential/non-essential amino acid ratios. In addition, 817C were noted to have highest content of microelements whereas AAB have highest content of potassium. Besides, 817C birds had particularly higher proportions of desirable fatty acids, essential fatty acids, polyunsaturated/saturated and (18:0+18:1)/16:0 ratios. The present study also revealed that there were significant differences on breast meat and thigh meat for the physicochemical and nutritional properties, regardless of chicken breeds. In conclusion, meat of crossbred chickens has some unique features and exhibited more advantages over commercial broilers and spent hens. Therefore, the current investigation would provide valuable information for the chicken meat product processing, and influence the consumption of different chicken meat