Thermal Shift Assay for Small GTPase Stability Screening: Evaluation and Suitability

Thermal unfolding methods are commonly used as a predictive technique by tracking the protein’s physical properties. Inherent protein thermal stability and unfolding profiles of biotherapeutics can help to screen or study potential drugs and to find stabilizing or destabilizing conditions. Differential scanning calorimetry (DSC) is a ‘Gold Standard’ for thermal stability assays (TSA), but there are also a multitude of other methodologies, such as differential scanning fluorimetry (DSF). The use of an external probe increases the assay throughput, making it more suitable for screening studies, but the current methodologies suffer from relatively low sensitivity. While DSF is an effective tool for screening, interpretation and comparison of the results is often complicated. To overcome these challenges, we compared three thermal stability probes in small GTPase stability studies: SYPRO Orange, 8-anilino-1-naphthalenesulfonic acid (ANS), and the Protein-Probe. We studied mainly KRAS, as a proof of principle to obtain biochemical knowledge through TSA profiles. We showed that the Protein-Probe can work at lower concentration than the other dyes, and its sensitivity enables effective studies with non-covalent and covalent drugs at the nanomolar level. Using examples, we describe the parameters, which must be taken into account when characterizing the effect of drug candidates, of both small molecules and Designed Ankyrin Repeat Proteins.     

Image cryptosystem based on plain image correlation rate and selective chaotic maps

In this paper, a new image encryption algorithm is introduced for encrypting grayscale digital images of any size. To improve the encryption evaluation parameters, we suggested that the value of the plain image correlation coefficient be effective in the cryptographic process, so plain images with different properties and correlation coefficient rates are encrypted in different ways. According to the average absolute value of correlation coefficient of plain image, Logistic or Tent maps is selected to generate chaotic sequences to expand plain image matrix. As the first step of the diffusion phase, the plain image matrix is developed with larger size by proper selected chaotic sequences, and simultaneously a chaotic matrix with the same size is generated by chaotic Sine map sequences. In confusion phase, the modified Lorenz map changes pixel locations of new developed matrix by means of certain equations. Then bitwise XOR is applied between developed matrix include plain image and Sine map chaotic matrix, as second step of diffusion phase. Finally, encrypted image is generated after applying exchange operations on the content of pixels, as third step of diffusion phase. Experimental results and comparisons with some of the existing methods, show that the proposed image cryptosystem is able to resist common cryptanalytic attacks and can be used as a secure method for encrypting digital images.

     

Purification of Barley Starch by Protein Extraction

Preparation of pure starch samples requires gentle extraction from the endosperm matrix, followed by removal of contaminating endosperm proteins. Published techniques for removal of these proteins include protease treatment or centrifugation through CsCI. We present a simple method to remove proteins from starch, exploiting the solubility of the major groups of endosperm proteins in aqueous, saline, and alcoholic solvents. The data show that the purity of the starch and retention of B-granules is similar to conventional techniques. Denaturing polyacry-lamide gel electrophoresis reveals very few proteins retained with the starch. One major protein has an apparent MW of 54000 and probably corresponds to the “waxy” protein, granule-bound starch synthase.     

Can deciduous tree revetments reduce streambank erosion rates on a sand-bed stream?

Accelerated streambank erosion can threaten infrastructure and land, as well as water quality and aquatic habitats. Streambank stabilization techniques have been developed with the intent to reduce or halt streambank erosion. One such technique is the use of woody revetments. This case study evaluates the effectiveness of deciduous tree revetments on stabilizing streambanks on the Smoky Hill River, a low-gradient, sand-bed stream located in central Kansas in the United States. It was hypothesized that deciduous tree revetments would mimic bank protection processes of permeable-type spurs, capturing sediment and reducing velocities and shear stresses near the toe of the streambank. To test this hypothesis, cross-sectional dimensions of four streambanks were obtained before and after installation of tree revetments and compared to four natural, control streambanks (i.e., not stabilized) over a 5-year period. Rates of bank erosion were calculated and compared. This study found that, in its current design form, deciduous tree revetments were not effective at reducing bank erosion, as all sites had experienced revetment failures by the end of the study period. Furthermore, the installation of tree revetments accelerated bank erosion rates following revetment failure. Increased bank erosion was attributed to both the construction disturbance, as well as improper anchoring of the revetment. The results of this case study show the importance of collecting bank stratigraphic data and incorporating it, as well as expected flow scenarios, in numerical modelling tools to assess designs and adjust accordingly. While conducting these analyses upfront may result in higher design costs, long-term maintenance or replacement costs would be decreased.