Methods optimization for the expression and purification of human calcium calmodulin-dependent protein kinase II alpha

Calcium/calmodulin-dependent protein kinase II (CaMKII) is a complex multifunctional kinase that is highly expressed in central nervous tissues and plays a key regulatory role in the calcium signaling pathway. Despite over 30 years of recombinant expression and characterization studies, CaMKII continues to be investigated for its impact on signaling cooperativity and its ability to bind multiple substrates through its multimeric hub domain. Here we compare and optimize protocols for the generation of full-length wild-type human calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα). Side-by-side comparison of expression and purification in both insect and bacterial systems shows that the insect expression method provides superior yields of the desired autoinhibited CaMKIIα holoenzymes. Utilizing baculovirus insect expression system tools, our results demonstrate a high yield method to produce homogenous, monodisperse CaMKII in its autoinhibited state suitable for biophysical analysis. Advantages and disadvantages of these two expression systems (baculovirus insect cell versus Escherichia coli expression) are discussed, as well as purification optimizations to maximize the enrichment of full-length CaMKII.

Immobilization of azide-functionalized proteins to micro- and nanoparticles directly from cell lysate

Immobilization of proteins and enzymes on solid supports has been utilized in a variety of applications, from improved protein stability on supported catalysts in industrial processes to fabrication of biosensors, biochips, and microdevices. A critical requirement for these applications is facile yet stable covalent conjugation between the immobilized and fully active protein and the solid support to produce stable, highly bio-active conjugates. Here, we report functionalization of solid surfaces (gold nanoparticles and magnetic beads) with bio-active proteins using site-specific and biorthogonal labeling and azide-alkyne cycloaddition, a click chemistry. Specifically, we recombinantly express and selectively label calcium-dependent proteins, calmodulin and calcineurin, and cAMP-dependent protein kinase A (PKA) with N-terminal azide-tags for efficient conjugation to nanoparticles and magnetic beads. We successfully immobilized the proteins on to the solid supports directly from the cell lysate with click chemistry, forgoing the step of purification. This approach is optimized to yield low particle aggregation and high levels of protein activity post-conjugation. The entire process enables streamlined workflows for bioconjugation and highly active conjugated proteins.

Selective Capture of Histidine-tagged Proteins from Cell Lysates Using TEM grids Modified with NTA-Graphene Oxide

We report the fabrication of transmission electron microscopy (TEM) grids bearing graphene oxide (GO) sheets that have been modified with N^α, N^α-dicarboxymethyllysine (NTA) and deactivating agents to block non-selective binding between GO-NTA sheets and non-target proteins. The resulting GO-NTA-coated grids with these improved antifouling properties were then used to isolate His₆-T7 bacteriophage and His₆-GroEL directly from cell lysates. To demonstrate the utility and simplified workflow enabled by these grids, we performed cryo-electron microscopy (cryo-EM) of His₆-GroEL obtained from clarified E. coli lysates. Single particle analysis produced a 3D map with a gold standard resolution of 8.1 Å. We infer from these findings that TEM grids modified with GO-NTA are a useful tool that reduces background and improves both the speed and simplicity of biological sample preparation for high-resolution structure elucidation by cryo-EM.

Who cares? Offering emotion work as a 'gift' in the nursing labour process

Who cares? Offering emotion work as a 'gift' in the nursing labour process The emotional elements of the nursing labour process are being recognized increasingly. Many commentators stress that nurses' 'emotional labour' is hard and productive work and should be valued in the same way as physical or technical labour. However, the term 'emotional labour' fails to conceptualize the many occasions when nurses not only work hard on their emotions in order to present the detached face of a professional carer, but also to offer authentic caring behaviour to patients in their care. Using qualitative data collected from a group of gynaecology nurses in an English National Health Service (NHS) Trust hospital, this paper argues that nursing work is emotionally complex and may be better understood by utilizing a combination of Hochschild's concepts: emotion work as a 'gift' in addition to 'emotional labour'. The gynaecology nurses in this study describe their work as 'emotionful' and therefore it could be said that this particular group of nurses represent a distinct example. Nevertheless, though it is impossible to generalize from limited data, the research presented in this paper does highlight the emotional complexity of the nursing labour process, expands the current conceptual analysis, and offers a path for future research. The examination further emphasizes the need to understand and value the motivations behind nurses' emotion work and their wish to maintain caring as a central value in professional nursing.

Optimization of a breath-hold magnetic resonance gradient echo technique for the detection of interstitial lung disease

RATIONALE AND OBJECTIVES

A rapid gradient echo technique was optimized to allow breath-held imaging of the lung parenchyma. The ability of this sequence to detect interstitial lung disease was then compared with high resolution computed tomography.

METHODS

A Turbo-FLASH gradient echo sequence (repetition time [TR] 4.7, echo time [TE]2) was optimized using four volunteers. The parameters varied, including flip angle, inversion time, slice thickness, and number of measurements per unit time. The effect on signal to noise ratio of lung inflation and position within the lung were also studied. The optimized sequence was then compared with high resolution computed tomography in five patients being investigated for interstitial lung disease.

RESULTS

Greatest signal was achieved using no inversion prepulse. This allowed up to six measurements, each with two acquisitions, during a single breath-hold. Optimum signal to noise ratio was achieved using a flip angle of 10 degrees with a 20-mm slice thickness, although a 10-mm slice was felt to be preferable for clinical use. Greatest signal to noise ratio was generated in the posterior aspect of the lung in full expiration. Comparison of the optimized magnetic resonance imaging technique with high resolution computed tomography showed no significant difference (P = 0.17) when assessing the proportion of diseased to normal lung.

CONCLUSIONS

Using standard magnetic resonance software and hardware, it has been possible to use a breath-hold sequence that allows detection and quantification of interstitial lung disease.