Scrambled 10Panx

Scrambled 10Panx is the scrambled form of 10Panx (WRQAAFVDSY), a mimetic peptide of pannexin 1 that inhibits dye uptake by macrophages without affecting cellular membrane currents. Being structurally similar to anther peptide PanxE1B, 10Panx is three amino acid shorter but exerting an inhibitory effect against pannexin1 currents in oocytes to a similar extent as PanxE1b. 10Panx is also able to block the activation of I_2nd, decrease the bradykinin-induced [Ca²⁺]_i response and attenuate bradykinin-induced ATP release from human fibroblasts loaded with quinacrine. However, in several studies, scrambled 10Panx has been proved to be less effective than 10Panx in its authentic form.

Reference

Roger J. Thompson, Michael F. Jackson, Michelle E. Olah, Ravi L. Rungta, Dustin J. Hines, Michael A. Beazely, John F. MacDonald, Brian A. MacVicar. Activation of Pannexin-1 hemichannels augments aberrant bursting in the hippocampus. Science 2008; 322: 1555-1559.

Ana Rita Pinheiro, Diogo Paramos-de-Carvalho, Marianna Certal, Cristina Costa, Maria Teresa Magalhaes-Cardoso, Fatima Ferreirinha, Maria Adelina Costa and Paulo Correia-de-Sa. Bradykinin-induced Ca²⁺ signaling in human subcutaneous fibroblasts involves ATP release via hemichannels leading to P2Y₁₂ receptors activation. Communication and Signaling 2013, 11:70

Junjie Wang, Meiyun Ma, Silviu Locovei, Robert W. Keane and Gerhard Dahl. Modulation of membrane channel currents by gap junction protein mimetic peptides: size matters. Am J Physiol Cell Physiol 293: C1112-C1119, 2007

Dynamic predictive model for growth of Salmonella spp. in scrambled egg mix.[Pubmed:28213033]

Food Microbiol. 2017 Jun;64:39-46.

Liquid egg products can be contaminated with Salmonella spp. during processing. A dynamic model for the growth of Salmonella spp. in scrambled egg mix - high solids (SEM) was developed and validated. SEM was prepared and inoculated with ca. 2 log CFU/mL of a five serovar Salmonella spp. cocktail. Salmonella spp. growth data at isothermal temperatures (10, 15, 20, 25, 30, 35, 37, 39, 41, 43, 45, and 47 degrees C) in SEM were collected. Baranyi model was used (primary model) to fit growth data and the maximum growth rate and lag phase duration for each temperature were determined. A secondary model was developed with maximum growth rate as a function of temperature. The model performance measures, root mean squared error (RMSE, 0.09) and pseudo-R(2) (1.00) indicated good fit for both primary and secondary models. A dynamic model was developed by integrating the primary and secondary models and validated using two sinusoidal temperature profiles, 5-15 degrees C (low temperature) for 480 h and 10-40 degrees C (high temperature) for 48 h. The RMSE values for the sinusoidal low and high temperature profiles were 0.47 and 0.42 log CFU/mL, respectively. The model can be used to predict Salmonella spp. growth in case of temperature abuse during liquid egg processing.

3D organization of synthetic and scrambled chromosomes.[Pubmed:28280150]

Science. 2017 Mar 10;355(6329). pii: 355/6329/eaaf4597.

Although the design of the synthetic yeast genome Sc2.0 is highly conservative with respect to gene content, the deletion of several classes of repeated sequences and the introduction of thousands of designer changes may affect genome organization and potentially alter cellular functions. We report here the Hi-C-determined three-dimensional (3D) conformations of Sc2.0 chromosomes. The absence of repeats leads to a smoother contact pattern and more precisely tractable chromosome conformations, and the large-scale genomic organization is globally unaffected by the presence of synthetic chromosome(s). Two exceptions are synIII, which lacks the silent mating-type cassettes, and synXII, specifically when the ribosomal DNA is moved to another chromosome. We also exploit the contact maps to detect rearrangements induced in SCRaMbLE (synthetic chromosome rearrangement and modification by loxP-mediated evolution) strains.

Amyloidogenicity and toxicity of the reverse and scrambled variants of amyloid-beta 1-42.[Pubmed:28185264]

FEBS Lett. 2017 Mar;591(5):822-830.

beta-amyloid 1-42 (Abeta1-42) is a self-assembling peptide that goes through many conformational and morphological changes before forming the fibrils that are deposited in extracellular plaques characteristic of Alzheimer's disease. The link between Abeta1-42 structure and toxicity is of major interest, in particular, the neurotoxic potential of oligomeric species. Many studies utilise reversed (Abeta42-1) and scrambled (AbetaS) forms of amyloid-beta as control peptides. Here, using circular dichroism, thioflavin T fluorescence and transmission electron microscopy, we reveal that both control peptides self-assemble to form fibres within 24 h. However, oligomeric Abeta reduces cell survival of hippocampal neurons, while Abeta42-1 and Abetas have reduced effect on cellular health, which may arise from their ability to assemble rapidly to form protofibrils and fibrils.

Scrambled Internal Standard Method for High-Throughput Protein Quantification by Matrix-Assisted Laser Desorption Ionization Tandem Mass Spectrometry.[Pubmed:28317378]

J Proteome Res. 2017 Apr 7;16(4):1556-1565.

Matrix-assisted laser desorption ionization (MALDI) could be advantageous for high-throughput MS acquisition but suffers from low signal reproducibility. The purpose of this study was to establish a reliable MALDI-tandem mass spectrometry (MS/MS)-based high-throughput quantification of tryptic peptides using our newly developed scrambled internal standard (sIS) method. The standard curves obtained with sIS peptides showed good linearity over a wide concentration range (5-1000 fmol/muL) compared to that with the IS-free method, and the coefficient of variation of data points at each concentration (5-1000 fmol/muL) was significantly reduced. Furthermore, the ion suppression effect of digested serum could be normalized with the sIS peptides. Differences of quantitative values obtained by MALDI-MS/MS and liquid chromatography-MS/MS with selected reaction monitoring were within 20% in the presence of 0.1-5 muL of immunoprecipitated model plasma. Furthermore, the effect of amino acid composition on peptide sensitivity was examined, and we found that sensitivity was significantly decreased if an aromatic amino acid was replaced with a nonaromatic amino acid. Thus, high sensitivity required the use of sIS peptides containing an aromatic amino acid. Finally, the sIS method enabled high-throughput quantification of tryptic peptides with high accuracy and a wide dynamic range.

Activation of pannexin-1 hemichannels augments aberrant bursting in the hippocampus.[Pubmed:19056988]

Science. 2008 Dec 5;322(5907):1555-9.

Pannexin-1 (Px1) is expressed at postsynaptic sites in pyramidal neurons, suggesting that these hemichannels contribute to dendritic signals associated with synaptic function. We found that, in pyramidal neurons, N-methyl-d-aspartate receptor (NMDAR) activation induced a secondary prolonged current and dye flux that were blocked with a specific inhibitory peptide against Px1 hemichannels; knockdown of Px1 by RNA interference blocked the current in cultured neurons. Enhancing endogenous NMDAR activation in brain slices by removing external magnesium ions (Mg2+) triggered epileptiform activity, which had decreased spike amplitude and prolonged interburst interval during application of the Px1 hemichannel blocking peptide. We conclude that Px1 hemichannel opening is triggered by NMDAR stimulation and can contribute to epileptiform seizure activity.

Modulation of membrane channel currents by gap junction protein mimetic peptides: size matters.[Pubmed:17652431]

Am J Physiol Cell Physiol. 2007 Sep;293(3):C1112-9.

Connexin mimetic peptides are widely used to assess the contribution of nonjunctional connexin channels in several processes, including ATP release. These peptides are derived from various connexin sequences and have been shown to attenuate processes downstream of the putative channel activity. Yet so far, no documentation of effects of peptides on connexin channels has been presented. We tested several connexin and pannexin mimetic peptides and observed attenuation of channel currents that is not compatible with sequence specific actions of the peptides. Connexin mimetic peptides inhibited pannexin channel currents but not the currents of the channel formed by connexins from which the sequence was derived. Pannexin mimetic peptides did inhibit pannexin channel currents but also the channels formed by connexin 46. The same pattern of effects was observed for dye transfer, except that the inhibition levels were more pronounced than for the currents. The channel inhibition by peptides shares commonalities with channel effects of polyethylene glycol (PEG), suggesting a steric block as a mechanism. PEG accessibility is in the size range expected for the pore of innexin gap junction channels, consistent with a functional relatedness of innexin and pannexin channels.

Pannexin-1 mediates large pore formation and interleukin-1beta release by the ATP-gated P2X7 receptor.[Pubmed:17036048]

EMBO J. 2006 Nov 1;25(21):5071-82.

P2X(7) receptors are ATP-gated cation channels; their activation in macrophage also leads to rapid opening of a membrane pore permeable to dyes such as ethidium, and to release of the pro-inflammatory cytokine, interleukin-1beta (IL-1beta). It has not been known what this dye-uptake path is, or whether it is involved in downstream signalling to IL-1beta release. Here, we identify pannexin-1, a recently described mammalian protein that functions as a hemichannel when ectopically expressed, as this dye-uptake pathway and show that signalling through pannexin-1 is required for processing of caspase-1 and release of mature IL-1beta induced by P2X(7) receptor activation.