Structural and biophysical characterization of Bacillus thuringiensis insecticidal proteins Cry34Ab1 and Cry35Ab1.

Bacillus thuringiensis strains are well known for the production of insecticidal proteins upon sporulation and these proteins are deposited in parasporal crystalline inclusions. The majority of these insect-specific toxins exhibit three domains in the mature toxin sequence. However, other Cry toxins are structurally and evolutionarily unrelated to this three-domain family and little is known of their three dimensional structures, limiting our understanding of their mechanisms of action and our ability to engineer the proteins to enhance their function.

Using attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) to study the molecular conformation of parchment artifacts in different macroscopic states.

Maintaining appropriate temperatures and relative humidity is considered essential to extending the useful life of parchment artifacts. Although the relationship between environmental factors and changes to the physical state of artifacts is reasonably understood, an improved understanding of the relationship between the molecular conformation and changes to the macroscopic condition of parchment is needed to optimize environmental conditions. Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FT-IR) analysis, the conformation of the molecular structure in selected parchment samples with specific macroscopic conditions, typically discoloration and planar deformations (e.

Effects of isopropanol on collagen fibrils in new parchment.

Background: Isopropanol is widely used by conservators to relax the creases and folds of parchment artefacts. At present, little is known of the possible side effects of the chemical on parchments main structural component- collagen. This study uses X-ray Diffraction to investigate the effects of a range of isopropanol concentrations on the dimensions of the nanostructure of the collagen component of new parchment.

A study of degradation of historic parchment using small-angle X-ray scattering, synchrotron-IR and multivariate data analysis.

Parchment has been in use for thousands of years and has been used as the writing or drawing support for many important historic works. A variety of analytical techniques is currently used for routine assessment of the degree of denaturation of historic parchment; however, because parchment has a heterogeneous nature, analytical methods with high spatial resolution are desirable. In this work, the use of small-angle X-ray scattering (SAXS) and synchrotron-IR (SR-IR) was examined in conjunction with multivariate data analysis to study degradation of an extended set of historic parchment samples, and particularly to investigate the effect of lipids and the presence of iron gall ink on the degradation processes.

The interaction of unfolding α-lactalbumin and malate dehydrogenase with the molecular chaperone αB-crystallin: a light and X-ray scattering investigation.

Purpose: The molecular chaperone αB-crystallin is found in high concentrations in the lens and is present in all major body tissues. Its structure and the mechanism by which it protects its target protein from aggregating and precipitating are not known.

Methods: Dynamic light scattering and X-ray solution scattering techniques were used to investigate structural features of the αB-crystallin oligomer when complexed with target proteins under mild stress conditions, i.

Use of attenuated total reflection-Fourier transform infrared spectroscopy to measure collagen degradation in historical parchments.

Developing a noninvasive method to assess the degraded state of historical parchments is essential to providing the best possible care for these documents. The conformational changes observed when collagen molecules, the primary constituent of parchment, unfold have been analyzed using attenuated total reflection-Fourier transform infrared (ATR-FT-IR) spectroscopy and the nanoscopic structural changes have been analyzed using X-ray diffraction (XRD). The relationship between the results obtained from these techniques was studied using principal component analysis, where correlation was found.

Changes in the molecular packing of fibrillin microfibrils during extension indicate intrafibrillar and interfibrillar reorganization in elastic response.

Fibrillin-rich microfibrils are the major structural components of the extracellular matrix that provide elasticity in a majority of connective tissues. The basis of elastic properties lies in the organization of fibrillin molecules, which, unfortunately, is still poorly understood. An X-ray diffraction study of hydrated fibrillin-rich microfibrils from zonular filaments has been conducted to give an insight into the molecular structure of microfibrils in intact tissue.

Marfan syndrome-causing mutations in fibrillin-1 result in gross morphological alterations and highlight the structural importance of the second hybrid domain.

Mutations in fibrillin-1 result in Marfan syndrome, which affects the cardiovascular, skeletal and ocular systems. The multiorgan involvement and wide spectrum of associated phenotypes highlights the complex pathogenesis underlying Marfan syndrome. To elucidate the genotype to phenotype correlations, we engineered four Marfan syndrome causing mutations into a fibrillin-1 fragment encoded by exons 18-25, a region known to interact with tropoelastin.

Microfibrillar structure of type I collagen in situ.

The fibrous collagens are ubiquitous in animals and form the structural basis of all mammalian connective tissues, including those of the heart, vasculature, skin, cornea, bones, and tendons. However, in comparison with what is known of their production, turnover and physiological structure, very little is understood regarding the three-dimensional arrangement of collagen molecules in naturally occurring fibrils. This knowledge may provide insight into key biological processes such as fibrillo-genesis and tissue remodeling and into diseases such as heart disease and cancer.

Microfocus X-ray scattering investigations of eggshell nanotexture.

The avian eggshell is a highly ordered calcitic bioceramic composite, with both inorganic and organic constituents. The interactions between the inorganic and organic components within the structure are poorly understood but are likely to occur at the nanometre level. Thus structural variation at this level may impinge on the overall structural integrity and mechanical performance of the eggshell, and therefore analysis at this level is fundamental in fully understanding this ordered structure.

The photoreactivity of ocular lipofuscin.

Lipofuscin or "age pigment" is a lipid-protein complex which accumulates in a variety of postmitotic, metabolically active cells throughout the body. These complexes, which are thought to result from the incomplete degradation of oxidised substrate, have the potential for photoreactivity. This is particularly so in the retina in which the lipofuscin not only contains retinoid metabolites but is also exposed to high oxygen and fluxes of visible light all of which provide an ideal environment for the generation of reactive oxygen species (ROS).

Mechanical properties of UV irradiated rat tail tendon (RTT) collagen.

The mechanical properties of RTT collagen tendon before and after UV irradiation have been investigated by mechanical testing (Instron). Air-dried tendon were submitted to treatment with UV irradiation (wavelength 254 nm) for different time intervals. The changes in such mechanical properties as breaking strength and percentage elongation have been investigated.

Ageing of the retinal pigment epithelium: implications for transplantation.

This review will discuss some of the implications for using cells from aged donors for retinal pigment epithelium (RPE) transplantation. It will consider age-related changes in the structure and function of RPE cells and the accumulation of potentially damaging photoreactive constituents. The review will focus on the role of the ocular pigments lipofuscin and melanin in respect to age-related changes in composition, photoreactivity and potential role in retinal ageing and age-related macular degeneration.

Polarized vibrational spectroscopy of fiber polymers: hydrogen bonding in cellulose II.

Vibrational spectroscopy using polarized incident radiation can be used to determine the orientation of X-H bonds with respect to coordinates such as crystallographic axes. The adaptation of this approach to polymer fibers is described here. It requires spectral intensity to be quantified around a 180 degrees range of polarization angles and not just recorded transversely and longitudinally as is normal in fiber spectroscopy.