A Method for the Structural Investigation of Membrane Proteins

We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i) the stabilization of membrane proteins in the meso phase, (ii) the control of hydration level and additive concentration by vapor diffusion. The new technology (iii) significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv) direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR) crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII) from Halobacterium salinarum for the first time

Controlled In Meso Phase Crystallization – A Method for the Structural Investigation of Membrane Proteins

We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i) the stabilization of membrane proteins in the meso phase, (ii) the control of hydration level and additive concentration by vapor diffusion. The new technology (iii) significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv) direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR) crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII) from Halobacterium salinarum for the first time

Expression and Purification of Functional Human Mu Opioid Receptor from E.coli

N-terminally his-tagged human mu opioid receptor, a G protein-coupled receptor was produced in E.coli employing synthetic codon-usage optimized constructs. The receptor was expressed in inclusion bodies and membrane-inserted in different E.coli strains. By optimizing the expression conditions the expression level for the membrane-integrated receptor was raised to 0.3-0.5 mg per liter of culture. Milligram quantities of receptor could be enriched by affinity chromatography from IPTG induced cultures grown at 18°C. By size exclusion chromatography the protein fraction with the fraction of alpha-helical secondary structure expected for a 7-TM receptor was isolated, by CD-spectroscopy an alpha-helical content of ca. 45% was found for protein solubilised in the detergent Fos-12. Receptor in Fos-12 micelles was shown to bind endomorphin-1 with a K(D) of 61 nM. A final yield of 0.17 mg functional protein per liter of culture was obtained

High-efficient production and biophysical characterisation of nicastrin, and ist interaction with APPC100

Nicastrin, the largest member among the four components of the γ-secretase complex, has been identified to be the substrate recognizer for the proteolytic activity of the complex. Here we report that full-length human nicastrin (hNCT) can be obtained by heterologous expression in E. coli. Milligram quantities of the target protein are purified in a two-step purification protocol using affinity chromatography followed by SEC. The FOS-choline 14 purified tetrameric hNCT exhibits a proper folding with 31% α-helix and 23% β-sheet content. Thermal stability studies reveal stable secondary and tertiary structure of the detergent purified hNCT. A physical interaction between nicastrin and the γ-secretase substrate APPC100 confirmed the functionality of hNCT as a substrate recognizer

Data on solubilization, identification, and thermal stability of human Presenilin-2

The data presented here are related to the research article entitled “Expression, purification, and preliminary characterization of human presenilin-2" [1].Human Presenilin-2 is the catalytic subunit of γ-secretase and a possible calcium leakage channel (Kimberly et al., 2000; Tu et al., 2006) [2,3]. HisPS2 which was obtained by overexpression in E. coli strain C43 (DE3) was extracted by detergent solubilisation. The sample isolation efficiency by detergents and the protein identification by mass spectrometry and western blot are described.This data article describes the near and far UV circular dichroism measurements and the data deconvolution in terms of secondary structure at 4 and 98 °C. Also, a refolding spectrum is presented.The raw CD spectra used for deconvolution of the helix and stand segments and average length are deposited into Protein Circular Dichroism Data Bank with PCDDBid: CD0005962000 (4 °C far UV), CD0005963000 (98 °C far UV), CD0005964000 (back to 4 °C far UV) and CD0005965000 (4 °C near UV CD)

Expression, purification, and preliminary characterization of human presenilin-2

Presenilins (PS1 and PS2) exhibit similar γ-secretase-dependent and −independent functions with subtle variations. In this study, we established a cost-effective process to overexpress and purify full-length human PS2 in sufficient quantities and quality for structural studies. Upon optimization, milligram quantities of homogeneous trimeric hisPS2 were purified, which enabled the preliminary characterization of human hisPS2 zymogen. Far-UV and near-UV CD as well as fluorescence spectroscopy revealed that purified hisPS2 contained the expected secondary structure and was folded into a defined tertiary structure. Thermal stability analysis revealed a Tm value of ∼55 °C for secondary structure while cholesterol significantly increased the stability. The low melting temperature of ∼34 °C for the tertiary structure was able to explain the purity and aggregation problems observed during purification. Additionally, the occurrence of calcium ions induced structural changes to different extents for PS2WT and PS2-D263A/D366A was observed, which is consistent with previous studies

Growth conditions of OPRM in different E.coli strains.

<p>Expression of OPRM was induced by IPTG. Cell culture density (OD₆₀₀) and weight of cell pellet (g) after different induction times with two different media (TB and DYT) was measured. Cell pellet (g) was obtained from 1 liter of culture medium.</p

Expression of the N-terminally his-tagged OPRM protein.

<p>Western blot on His-tag. A, Expression by autoinduction at 37°C in different E.coli strains (RP, RIL, C41, and C43). Lane 1 - uninduced, lane 2–Inclusion body fraction (induced 4 h), lane 3–Membrane fraction (induced 4 h), lane 4–Inclusion body fraction (induced 20 h), lane 5–Membrane fraction (induced 20 h). B, Optimised expression of OPRM using C43 cells, TB medium with 0.4 mM IPTG at 18°C. Western blot showed inclusion body (IB) and membrane fractions (M) of OPRM.</p