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Tribst A.A.L.,University of Campinas | Cota J.,University of Campinas | Cota J.,CTBE - Brazilian Bioethanol Science and Technology Laboratory | Murakami M.T.,Brazilian Biosciences National Laboratory LNBio CNPEM | Cristianini M.,University of Campinas
PLoS ONE | Year: 2014

High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO. © 2014 Tribst et al. Source

Nogueira M.L.C.,Brazilian Biosciences National Laboratory LNBio CNPEM | Sforca M.L.,Brazilian Biosciences National Laboratory LNBio CNPEM | Chin Y.K.-Y.,University of Queensland | Mobli M.,University of Queensland | And 6 more authors.
Biomolecular NMR Assignments | Year: 2015

Bacterial division begins with the formation of a contractile protein ring at midcell, which constricts the bacterial envelope to generate two daughter cells. The central component of the division ring is FtsZ, a tubulin-like protein capable of self-assembling into filaments which further associate into a higher order structure known as the Z ring. Proteins that bind to FtsZ play a crucial role in the formation and regulation of the Z ring. One such protein is ZapA, a widely conserved 21 kDa homodimeric protein that associates with FtsZ filaments and promotes their bundling. Although ZapA was discovered more than a decade ago, the structural details of its interaction with FtsZ remain unknown. In this work, backbone and side chain NMR assignments for the Geobacillus stearothermophilus ZapA homodimer are described. We titrated FtsZ into 15N2H-ZapA and mapped ZapA residues whose resonances are perturbed upon FtsZ binding. This information provides a structural understanding of the interaction between FtsZ and ZapA. © 2015, Springer Science+Business Media Dordrecht. Source

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