Chromato-panning: an efficient new mode of identifying suitable ligands from phage display libraries

<p>Abstract</p> <p>Background</p> <p>Phage Display technology is a well established technique for high throughput screening of affinity ligands. Here we describe a new compact chromato-panning procedure for selection of suitable binders from a phage peptide display library.</p> <p>Results</p> <p>Both phages and <it>E. coli </it>cells pass non-hindered through the interconnected pores of macroporous gel, so called <it>cryogel</it>. After coupling a ligand to a monolithic cryogel column, the phage library was applied on the column and non-bound phages were washed out. The selection of strong phage-binders was achieved already after the first panning cycle due to the efficient separation of phage-binders from phage-non-binders in chromatographic mode rather than in batch mode as in traditional biopanning procedures. <it>E. coli </it>cells were applied on the column for infection with the specifically bound phages.</p> <p>Conclusion</p> <p>Chromato-panning allows combining several steps of the panning procedure resulting in 4–8 fold decrease of total time needed for phage selection.</p

Clifford-Jacobs Forging Company v. Capital Engineering & (and) Manufacturing Co.: The Continuing Problem within U.C.C. Section 2-207, 16 J. Marshall L. Rev. 589 (1983)

status: accepte

The novel S527F mutation in the integrin beta3 chain induces a high affinity alphaIIbbeta3 receptor by hindering adoption of the bent conformation.

peer reviewedThree heterozygous mutations were identified in the genes encoding platelet integrin receptor alphaIIbbeta3 in a patient with an ill defined platelet disorder: one in the beta3 gene (S527F) and two in the alphaIIb gene (R512W and L841M). Five stable Chinese hamster ovary cell lines were constructed expressing recombinant alphaIIbbeta3 receptors bearing the individual R512W, L841M, or S527F mutation; both the R512W and L841M mutations; or all three mutations. All receptors were expressed on the cell surface, and mutations R512W and L841M had no effect on integrin function. Interestingly, the beta3 S527F mutation produced a constitutively active receptor. Indeed, both fibrinogen and the ligand-mimetic antibody PAC-1 bound to non-activated alphaIIbbeta3 receptors carrying the S527F mutation, indicating that the conformation of this receptor was altered and corresponded to the high affinity ligand binding state. In addition, the conformational change induced by S527F was evident from basal anti-ligand-induced binding site antibody binding to the receptor. A molecular model bearing this mutation was constructed based on the crystal structure of alphaIIbbeta3 and revealed that the S527F mutation, situated in the third integrin epidermal growth factor-like (I-EGF3) domain, hindered the alphaIIbbeta3 receptor from adopting a wild type-like bent conformation. Movement of I-EGF3 into a cleft in the bent conformation may be hampered both by steric hindrance between Phe(527) in beta3 and the calf-1 domain in alphaIIb and by decreased flexibility between I-EGF2 and I-EGF3

Major Changes of von Willebrand Factor Multimer Distribution in Cirrhotic Patients with Stable Disease or Acute Decompensation

Background There is an unstable balance between pro- and anti-haemostatic processes in patients with cirrhosis. We hypothesized, that in patients with acute decompensation (AD) the major alterations of von Willebrand factor (VWF) could contribute to the pro thrombotic situation as compared to patients with stable (ST) cirrhosis. Patients and Methods We analysed different parameters of VWF, including detailed multimer distribution by densitometry and platelet adhesion, together with a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs 13 (ADAMTS13) activity and antigen and C-reactive protein (CRP) levels in patients with ST cirrhosis (n = 99), with AD (n = 54) and controls (n = 92). Results VWF antigen, ristocetin co-factor as well as collagen-binding activities were elevated in both cirrhotic groups in a stepwise manner. There was a decrease in high and an increase in low molecular weight multimer ratios in the majority of ST cirrhosis. However, in 24 out of 54 AD patients, ultra-large VWF multimers (ultra-large molecular weight multimers [ULMWM]) were found. ADAMTS13 activity in ST and AD patients without ULMWM was similar to controls (median [interquartile range; IQR]%: 98 [67-132] and 91 [60-110] vs. 106 [88-117], respectively). The presence of ULMWM in AD patients was associated with low ADAMTS13 activity [33 (24-49)%] and high CRP level [23 (7.1-83.6) mg/L]. Adhesion of normal platelets showed a stepwise increase in the presence of cirrhotic plasmas, reaching the highest level in AD patients with ULMWM. Conclusion Characteristic changes of VWF parameters are seen in ST cirrhosis. In AD patients, highly increased VWF and reduced ADAMTS13 activity could be found, along with the presence of ULMWM, which are possible markers and contributors of the disease progression

Dryland mechanisms could widely control ecosystem functioning in a drier and warmer world

Responses of terrestrial ecosystems to climate change have been explored in many regions worldwide. While continued drying and warming may alter process rates and deteriorate the state and performance of ecosystems, it could also lead to more fundamental changes in the mechanisms governing ecosystem functioning. Here we argue that climate change will induce unprecedented shifts in these mechanisms in historically wetter climatic zones, towards mechanisms currently prevalent in dry regions, which we refer to as ‘dryland mechanisms’. We discuss 12 dryland mechanisms affecting multiple processes of ecosystem functioning, including vegetation development, water flow, energy budget, carbon and nutrient cycling, plant production and organic matter decomposition. We then examine mostly rare examples of the operation of these mechanisms in non-dryland regions where they have been considered irrelevant at present. Current and future climate trends could force microclimatic conditions across thresholds and lead to the emergence of dryland mechanisms and their increasing control over ecosystem functioning in many biomes on Earth.The support of the Israel Science Foundation is acknowledged by J.M.G. (grant number 1796/19), O.A. (1185/17) and E.M. (1053/17). M.B. acknowledges funding through the ÖAW-ESS project ClimGrassHydro (Austrian Academy of Sciences).Peer reviewe

Appropriation of GPIb from platelet-derived extracellular vesicles supports monocyte recruitment in systemic inflammation

Interactions between platelets, leukocytes and the vessel wall provide alternative pathological routes of thrombo-inflammatory leukocyte recruitment. We found that when platelets were activated by a range of agonists in whole blood, they shed platelet-derived extracellular vesicles which rapidly and preferentially bound to blood monocytes compared to other leukocytes. Platelet-derived extracellular vesicle binding to monocytes was initiated by P-selectin-dependent adhesion and was stabilised by binding of phosphatidylserine. These interactions resulted in the progressive transfer of the platelet adhesion receptor GPIbα to monocytes. GPIbα+-monocytes tethered and rolled on immobilised von Willebrand Factor or were recruited and activated on endothelial cells treated with TGF-β1 to induce the expression of von Willebrand Factor. In both models monocyte adhesion was ablated by a function-blocking antibody against GPIbα. Monocytes could also bind platelet-derived extracellular vesicle in mouse blood in vitro and in vivo. Intratracheal instillations of diesel nanoparticles, to model chronic pulmonary inflammation, induced accumulation of GPIbα on circulating monocytes. In intravital experiments, GPIbα+-monocytes adhered to the microcirculation of the TGF-β1-stimulated cremaster muscle, while in the ApoE−/− model of atherosclerosis, GPIbα+-monocytes adhered to the carotid arteries. In trauma patients, monocytes bore platelet markers within 1 hour of injury, the levels of which correlated with severity of trauma and resulted in monocyte clearance from the circulation. Thus, we have defined a novel thrombo-inflammatory pathway in which platelet-derived extracellular vesicles transfer a platelet adhesion receptor to monocytes, allowing their recruitment in large and small blood vessels, and which is likely to be pathogenic

Development and screening of epoxy-spacer-phage cryogels for affinity chromatography: Enhancing the binding capacity

Macroporous epoxy cryogels can be used as an alternative for classical matrices in affinity chromatography. Due to the structural properties of cryogels, with pores of up to 100 μm, crude samples can be processed at high speed without previous manipulations such as clarification or centrifugation. Also, we previously used a peptide-expressing M13 bacteriophage as an affinity ligand. These ligands show high specificity toward the target to be purified. Combination of both, leads to a relative cost-effective one-step chromatographic set-up delivering a high purity sample (>95%), however, so far with limited capacity. To increase the binding capacity of the affinity columns, we now inserted spacers between the chromatographic matrix and the phage ligand. Both linear spacers, di-amino-alkanes (C2 -C10 ), and branched polyethyleneimine spacers with different molecular weights (800 Da-10 kDa) were analyzed. Two types of peptide expressing phage ligands, a linear 15-mer and a cyclic 6-mer, were used for screening. Up to a tenfold increase in binding capacity was observed depending on the combination of phage ligand and spacer type.status: publishe

When collagen meets VWF

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