Protein/lipid interactions in phospholipid monolayers containing the bacterial antenna protein B800-850

Studies on monomolecular layers of phospholipids containing the antenna protein B800-850 (LHCP) and in some cases additionally the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides are reported. Information on monolayer preparation as well as on protein /lipid and protein/protein interaction is obtained by means of fluorescence spectroscopy and microscopy at the air/water interface in combination with film balance experiments. It is shown that a homogeneous distribution of functional proteins can be achieved. This can be transformed into a regular pattern-like distribution by inducing a phospholipid phase transition. Although the LHCP preferentially partitions into the fluid lipid phase, it decreases the lateral pressure necessary to crystallize the lipid. This is probably due to an increase in order of the fluid phase. A pressure-induced conformation change of the LHCP is detected via a drastic change in fluorescence yield. A highly efficient energy transfer from LHCP to the reaction center is observed. This proves the quantitative reconstitution of both types of proteins and indicates protein aggregation also in the monolayer

A range expanding signal conditioner

Telemetry system modifications to improve signal resolution are described. Process uses zero suppression technique which consists of subtracting known voltage from input and amplifying remainder. Schematic diagram of circuit is provided and details of operation are presented

Analyzing lower extremity injury profiles of pedestrian traffic fatalities according to vehicle type

Skeletal trauma analysis of motor vehicle collisions has the potential to support or contradict reported collision circumstances. This project analyzed the skeletal injuries that pedestrians sustain in fatal collisions according to vehicle types (car, truck, SUV, van, bus, semi, etc.). Data were collected from reports and databases related to cases that occurred in King County, Washington. The pelvis and lower extremities of the body were analyzed for the frequency of skeletal fractures, grouped by pelvis, femora, patellae, tibiae, and fibulae skeletal groups. A Kruskal-Wallis test showed an overall no significant difference (P\u3c0.05) in fracture quantity in skeletal regions between different vehicle groups. A multiple pairwise comparison using Dunn’s procedure also found no significant differences between vehicle type groups. A Partial Least Squares Discriminant Analysis showed an overall success rate of 37.29% when classifying injury profiles to vehicle type. The findings of this project can be applied to further research into the skeletal analysis of automobile versus pedestrian collisions. Low classification rates suggest that fracture frequency alone should not be used to assist in associating injuries with potential vehicle types in medicolegal investigations. Rather, the findings of this project lead the researcher to recommend that investigators and forensic practitioners move towards standardization in the quality and type of collected data—specific recommendations being the collection of actual speed and inclusion of full-body imaging in postmortem examinations to enable more detailed analyses

The Dynamic Transition of Protein Hydration Water

Thin layers of water on biomolecular and other nanostructured surfaces can be supercooled to temperatures not accessible with bulk water. Chen et al. [PNAS 103, 9012 (2006)] suggested that anomalies near 220 K observed by quasi-elastic neutron scattering can be explained by a hidden critical point of bulk water. Based on more sensitive measurements of water on perdeuterated phycocyanin, using the new neutron backscattering spectrometer SPHERES, and an improved data analysis, we present results that show no sign of such a fragile-to-strong transition. The inflection of the elastic intensity at 220 K has a dynamic origin that is compatible with a calorimetric glass transition at 170 K. The temperature dependence of the relaxation times is highly sensitive to data evaluation; it can be brought into perfect agreement with the results of other techniques, without any anomaly.Comment: 4 pages, 3 figures. Phys. Rev. Lett. (in press