Browsing by Subject "Protein stability"

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  • Lipiäinen, Tiina; Räikkönen, Heikki; Kolu, Anna-Maija; Peltoniemi, Marikki; Juppo, Anne (2018)
    Spray-dried protein formulations commonly require stabilising excipients to prevent protein degradation during processing and storage, and trehalose has been commonly used. The purpose of this work was to evaluate melibiose in spray-dried protein formulations in comparison to trehalose. The protein-activity-preserving efficacy, process behaviour and storage stability were studied. Spray drying of beta-galactosidase was carried out using different process temperature, drying air flow and feed liquid atomisation settings. Both melibiose and trehalose reduced protein activity loss during drying. A decrease in activities was observed when the process temperature exceeded a threshold temperature. During storage (30 days at 18% RH and 20 or 40 degrees C), the formulations dried below this threshold temperature showed no further activity loss, and the stabilising efficacy of the two disaccharides was equal. With higher process temperatures, the remaining protein activities after storage trended higher with melibiose formulations. All formulations remained amorphous. The powder yields of melibiose formulations were similar to trehalose. There was a difference in residual moisture contents, with melibiose formulations giving drier products. In conclusion, protein formulations with melibiose could be spray dried into amorphous powders that were physically stable, contained lower moisture contents and protected protein activity at least as well as trehalose formulations.
  • Laulumaa, Saara; Nieminen, Tuomo; Raasakka, Arne; Krokengen, Oda C.; Safaryan, Anushik; Hallin, Erik I.; Brysbaert, Guillaume; Lensink, Marc F.; Ruskamo, Salla; Vattulainen, Ilpo; Kursula, Petri (2018)
    Background: Myelin is a multilayered proteolipid sheath wrapped around selected axons in the nervous system. Its constituent proteins play major roles in forming of the highly regular membrane structure. P2 is a myelin-specific protein of the fatty acid binding protein (FABP) superfamily, which is able to stack lipid bilayers together, and it is a target for mutations in the human inherited neuropathy Charcot-Marie-Tooth disease. A conserved residue that has been proposed to participate in membrane and fatty acid binding and conformational changes in FABPs is Phe57. This residue is thought to be a gatekeeper for the opening of the portal region upon ligand entry and egress. Results: We performed a structural characterization of the F57A mutant of human P2. The mutant protein was crystallized in three crystal forms, all of which showed changes in the portal region and helix a2. In addition, the behaviour of the mutant protein upon lipid bilayer binding suggested more unfolding than previously observed for wild-type P2. On the other hand, membrane binding rendered F57A heat-stable, similarly to wild-type P2. Atomistic molecular dynamics simulations showed opening of the side of the discontinuous beta barrel, giving important indications on the mechanism of portal region opening and ligand entry into FABPs. The results suggest a central role for Phe57 in regulating the opening of the portal region in human P2 and other FABPs, and the F57A mutation disturbs dynamic cross-correlation networks in the portal region of P2. Conclusions: Overall, the F57A variant presents similar properties to the P2 patient mutations recently linked to Charcot-Marie-Tooth disease. Our results identify Phe57 as a residue regulating conformational changes that may accompany membrane surface binding and ligand exchange in P2 and other FABPs.
  • Laulumaa, Saara; Nieminen, Tuomo; Raasakka, Arne; Krokengen, Oda C; Safaryan, Anushik; Hallin, Erik I; Brysbaert, Guillaume; Lensink, Marc F; Ruskamo, Salla; Vattulainen, Ilpo; Kursula, Petri (BioMed Central, 2018)
    Abstract Background Myelin is a multilayered proteolipid sheath wrapped around selected axons in the nervous system. Its constituent proteins play major roles in forming of the highly regular membrane structure. P2 is a myelin-specific protein of the fatty acid binding protein (FABP) superfamily, which is able to stack lipid bilayers together, and it is a target for mutations in the human inherited neuropathy Charcot-Marie-Tooth disease. A conserved residue that has been proposed to participate in membrane and fatty acid binding and conformational changes in FABPs is Phe57. This residue is thought to be a gatekeeper for the opening of the portal region upon ligand entry and egress. Results We performed a structural characterization of the F57A mutant of human P2. The mutant protein was crystallized in three crystal forms, all of which showed changes in the portal region and helix α2. In addition, the behaviour of the mutant protein upon lipid bilayer binding suggested more unfolding than previously observed for wild-type P2. On the other hand, membrane binding rendered F57A heat-stable, similarly to wild-type P2. Atomistic molecular dynamics simulations showed opening of the side of the discontinuous β barrel, giving important indications on the mechanism of portal region opening and ligand entry into FABPs. The results suggest a central role for Phe57 in regulating the opening of the portal region in human P2 and other FABPs, and the F57A mutation disturbs dynamic cross-correlation networks in the portal region of P2. Conclusions Overall, the F57A variant presents similar properties to the P2 patient mutations recently linked to Charcot-Marie-Tooth disease. Our results identify Phe57 as a residue regulating conformational changes that may accompany membrane surface binding and ligand exchange in P2 and other FABPs.