Early Events, Kinetic Intermediates and the Mechanism of Protein Folding in Cytochrome c

Kinetic studies of the early events in cytochrome c folding are reviewed with a focus on the evidence for folding intermediates on the submillisecond timescale. Evidence from time-resolved absorption, circular dichroism, magnetic circular dichroism, fluorescence energy and electron transfer, small-angle X-ray scattering and amide hydrogen exchange studies on the t ≤ 1 ms timescale reveals a picture of cytochrome c folding that starts with the ~ 1-μs conformational diffusion dynamics of the unfolded chains. A fractional population of the unfolded chains collapses on the 1 – 100 μs timescale to a compact intermediate I_C containing some native-like secondary structure. Although the existence and nature of I_C as a discrete folding intermediate remains controversial, there is extensive high time-resolution kinetic evidence for the rapid formation of I_C as a true intermediate, i.e., a metastable state separated from the unfolded state by a discrete free energy barrier. Final folding to the native state takes place on millisecond and longer timescales, depending on the presence of kinetic traps such as heme misligation and proline mis-isomerization. The high folding rates observed in equilibrium molten globule models suggest that I_C may be a productive folding intermediate. Whether it is an obligatory step on the pathway to the high free energy barrier associated with millisecond timescale folding to the native state, however, remains to be determined.     

Probing kinetic mechanisms of protein function and folding with time-resolved natural and magnetic chiroptical spectroscopies

Recent and ongoing developments in time-resolved spectroscopy have made it possible to monitor circular dichroism, magnetic circular dichroism, optical rotatory dispersion, and magnetic optical rotatory dispersion with nanosecond time resolution. These techniques have been applied to determine structural changes associated with the function of several proteins as well as to determine the nature of early events in protein folding. These studies have required new approaches in triggering protein reactions as well as the development of time-resolved techniques for polarization spectroscopies with sufficient time resolution and sensitivity to probe protein structural changes.     

Screening,characterization, and biocatalytic capacity of lipases producing wild yeasts from Brazil biomes

The objective of this study was to develop a rice porridge containing perilla oil rich in α-linolenic acid which demonstrated anti-atherogenic effect in the previous study. Lipid lowering effect of emulsified perilla oil (EPO) was examined in apo E KO mice (n=18) and that for rice porridge containing EPO (RPEPO) was investigated in the pilot scale human study (n=20). Inhibitory effects of EPO on the plasma lipid levels and fatty streak lesion size in apo E KO mice were similar to those observed in mice fed perilla oil (PO), suggesting that EPO is applicable form of PO in manufacturing rice porridge product with PO’s health benefit properties. In human study with young adults aged between 20–35 years old, changes in plasma triglyceride concentration of subjects consumed RPEPO for 30 days as a breakfast was significantly lowered than those for subjects consumed rice porridge (p<0.05), of which calorie levels were the same (333 kcal/meal).     

Carbon dioxide fixation by microalgae cultivated in open bioreactors

The biofixation of carbon dioxide (CO₂) by microalgae has been proven to be an efficient and economical method, mainly due to the photosynthetic ability of these microorganisms to use this gas as a source of nutrients for their development. The aim of this work was to study the growth of Spirulina LEB18 and Chlorella kessleri microalgae, exposed to controlled and non-controlled conditions, with the injection of different concentrations of CO₂. The cultures was carried out in 6 L open raceway ponds, under controlled conditions at 30 °C and 39 μE m^?2 s^?1 and under non-controlled conditions, protected by a tunnel of transparent film. The experiments were subjected to CO₂ injections at concentrations of 0.038, 6, 12 and 18% (v/v). The highest concentration of biomass (4.95 g L^?1) and maximum daily fixation (0.21 g g^?1 d^?1) were obtained for Spirulina LEB18 in culture that was prepared in non-controlled conditions with an injection of 6% (v/v) of CO₂. C. kessleri had maximum (p < 0.0008) specific growth rate (0.84 d^?1) when grown with 18% (v/v) of CO₂ in non-controlled conditions of cultivation.     

Familial coping with cancer in childhood and adolescence. Possibilities for standardized assessment with a self-assessment method: results of an empirical pilot study

44 parents of pediatric oncology patients answered mailed questionnaires about their own coping and about their sick children's coping and bodily complaints during oncological therapy. Most of the families coped well from parents' view. The dominant coping style of the parents consisted of active, problem-focused coping strategies in combination with an optimistic basic attitude, maintainance of family cohesion and belief in god or search for a meaning of the illness. The children and adolescents used predominantly adaptive coping strategies. The parental problem-group with a predominantly maladaptive coping-style reported low family cohesion, high depression, high wishful thinking and minimization. The maladaptive children and adolescents were rated as more socially withdrawing, more irritable, less optimistic and competent as well as less compliant. Strong correlations were found between parents' and their children's coping. Problem families with a special need for psychosocial support can early be identified by the coping questionnaires used in this study. Prospective longitudinal studies with multi-methodal and multi-perspective designs should be conducted to reach a better understanding of the family coping process in case of childhood and adolescence cancer.     

Identification of Potential Probiotics Producing Bacteriocins Active against Listeria monocytogenes by a Combination of Screening Tools

Listeria monocytogenes is an important food-borne pathogen and a serious concern to food industries. Bacteriocins are antimicrobial peptides produced naturally by a wide range of bacteria mostly belonging to the group of lactic acid bacteria (LAB), which also comprises many strains used as starter cultures or probiotic supplements. Consequently, multifunctional strains that produce bacteriocins are an attractive approach to combine a green-label approach for food preservation with an important probiotic trait. Here, a collection of bacterial isolates from raw cow’s milk was typed by 16S rRNA gene sequencing and MALDI-Biotyping and supernatants were screened for the production of antimicrobial compounds. Screening was performed with live Listeria monocytogenes biosensors using a growth-dependent assay and pHluorin, a pH-dependent protein reporting membrane damage. Purification by cation exchange chromatography and further investigation of the active compounds in supernatants of two isolates belonging to the species Pediococcus acidilactici and Lactococcus garvieae suggest that their antimicrobial activity is related to heat-stable proteins/peptides that presumably belong to the class IIa bacteriocins. In conclusion, we present a pipeline of methods for high-throughput screening of strain libraries for potential starter cultures and probiotics producing antimicrobial compounds and their identification and analysis.     

Low-Cost Fabrication of Tungsten-Rhenium Alloys for Friction Stir Welding Applications

Metallurgical and Materials Transactions B - Friction stir welding (FSW) of high-melting temperature alloys, such as steel and Inconel, requires tooling that can survive under the applied loads at...