Water‐in‐Oil Micro‐Emulsion Enhances the Secondary Structure of a Protein by Confinement

Shipovskov, Stepan; Oliveira, Cristiano L. P.; Hoffmann, Søren Vrønning; Schauser, Leif; Sutherland, Duncan S.; Besenbacher, Flemming; Pedersen, Jan Skov

doi:10.1002/cphc.201200295

Cited by 12 publications

(9 citation statements)

References 32 publications

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“…For the MASP-1 dimer alone, data were collected from samples at concentrations of 0.87, 1.53, 1.75, and 3.49 mg ml À1 . The data were extrapolated to zero concentration as described in Shipovskov et al (2012). The maximum diameter D max of the complexes was estimated from the distance distribution function p(r) obtained by the program GNOM.…”

Section: Saxs Data Collection and Analysismentioning

confidence: 99%

Structural Insights into the Initiating Complex of the Lectin Pathway of Complement Activation

Kjær

Pedersen

et al. 2015

Structure

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The proteolytic cascade of the complement system is initiated when pattern-recognition molecules (PRMs) bind to ligands, resulting in the activation of associated proteases. In the lectin pathway of complement, the complex of mannan-binding lectin (MBL) and MBL-associated serine protease-1 (MASP-1) initiates the pathway by activating a second protease, MASP-2. Here we present a structural study of a PRM/MASP complex and derive the overall architecture of the 450 kDa MBL/MASP-1 complex using small-angle X-ray scattering and electron microscopy. The serine protease (SP) domains from the zymogen MASP-1 dimer protrude from the cone-like MBL tetramer and are separated by at least 20 nm. This suggests that intracomplex activation within a single MASP-1 dimer is unlikely and instead supports intercomplex activation, whereby the MASP SP domains are accessible to nearby PRM-bound MASPs. This activation mechanism differs fundamentally from the intracomplex initiation models previously proposed for both the lectin and the classical pathway.

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Section: Saxs Data Collection and Analysismentioning

confidence: 99%

Structural Insights into the Initiating Complex of the Lectin Pathway of Complement Activation

Kjær

Pedersen

et al. 2015

Structure

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“…The polydispersity of the molecular weights may also allow the OPN mix to somewhat stabilize precursor droplets better than the relatively monodisperse pAsp because there would be more molecules to interact at surfaces of droplets. Another possible reason that the OPN mix may stabilize more droplets than pAsp is that OPN may exhibit some secondary structure [68] (due to its negative, positive, and hydrophobic domains). Computational predictions suggest that although OPN is a highly disordered structure, it may form some short α-helices, and/or it may change its conformation upon binding to collagen [23].…”

Section: Discussionmentioning

confidence: 99%

Comparison of Synthetic vs. Biogenic Polymeric Process-Directing Agents for Intrafibrillar Mineralization of Collagen

et al. 2022

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With the aging population, there is a growing need for mineralized tissue restoration and synthetic bone substitutes. Previous studies have shown that a polymer-induced liquid-precursor (PILP) process can successfully mineralize collagen substrates to achieve compositions found in native bone and dentin. This process also leads to intrafibrillar apatitic crystals with their [001] axes aligned roughly parallel to the long axis of the collagen fibril, emulating the nanostructural organization found in native bone and dentin. When demineralized bovine bone was remineralized via the PILP process using osteopontin (OPN), the samples were able to activate mouse marrow-derived osteoclasts to similar levels to those of native bone, suggesting a means for fabricating bioactive bone substitutes that could trigger remodeling through the native bone multicellular unit (BMU). In order to determine if OPN derived from bovine milk could be a cost-effective process-directing agent, the mineralization of type I collagen scaffolds using this protein was compared to the benchmark polypeptide of polyaspartic acid (sodium salt; pAsp). In this set of experiments, we found that OPN led to much faster and more uniform mineralization when compared with pAsp, making it a cheaper and commercially attractive alternative for mineralized tissue restorations.

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“…The OPN structure can be constrained by immobilization, as is the case with amine coupling on a metal film (the surface plasmon resonance experiments of this study) or inside micro-emulsion droplets [25]. Yet, it is important to correlate these artificial in vitro conditions with physiologic environments.…”

Section: Discussionmentioning

confidence: 99%

Structural Constraint of Osteopontin Facilitates Efficient Binding to CD44

et al. 2021

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Since the original description in 1996, the interaction between the cytokine osteopontin (OPN) and the homing receptor CD44 has been extensively studied in cancer, inflammation, bone remodeling, and various other conditions. Alternative splicing and extensive posttranslational modifications by both binding partners, as well as the possibility for lateral recruitment of additional membrane receptors or soluble co-ligands into a complex have left the exact molecular requirements for high-affinity OPN-CD44 binding unresolved. We now report that there is a moderate engagement between the unmodified molecules, which results in curved double-reciprocal plots for OPN titration, suggesting the existence of two binding sites or two binding conformations. Structural constraint of OPN, by immobilization or by addition of heparin, is required for its strong ligation of CD44. Prior literature provides evidence that heparin binding to OPN prompts the unfolding of a core element in the protein. This conformational adjustment may be essential for efficient CD44 interaction. The integrin α9β1 seems to compete with the OPN-CD44 engagement, while the integrin αVβ3 reflects additive binding, suggesting that the CD44 contact sites on OPN are downstream of the RGD motif but overlap with the SVVYGLR domain. Hyaluronate has no effect, placing the relevant domain on CD44 downstream of the N-terminus.

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Water‐in‐Oil Micro‐Emulsion Enhances the Secondary Structure of a Protein by Confinement

Cited by 12 publications

References 32 publications

Structural Insights into the Initiating Complex of the Lectin Pathway of Complement Activation

Structural Insights into the Initiating Complex of the Lectin Pathway of Complement Activation

Comparison of Synthetic vs. Biogenic Polymeric Process-Directing Agents for Intrafibrillar Mineralization of Collagen

Structural Constraint of Osteopontin Facilitates Efficient Binding to CD44

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