| 1. |
- Lamberg, P., et al.
(författare)
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Electrical activity of cellobiose dehydrogenase adsorbed on thiols : Influence of charge and hydrophobicity
- 2017
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Ingår i: Bioelectrochemistry. - : Elsevier. - 1567-5394 .- 1878-562X. ; 115, s. 26-32
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Tidskriftsartikel (refereegranskat)abstract
- The interface between protein and material surface is of great research interest in applications varying from implants, tissue engineering to bioelectronics. Maintaining functionality of bioelements depends greatly on the immobilization process. In the present study direct electron transfer of cellobiose dehydrogenase from Humicola insolens (HiCDH), adsorbed on four different self-assembled monolayers (SAMs) formed by 5-6 chain length carbon thiols varying in terminal group structure was investigated. By using a combination of quartz crystal micro balance with dissipation, ellipsometry and electrochemistry the formation and function of the HiCDH film was studied. It was found that the presence of charged pyridinium groups was needed to successfully establish direct electron contact between the enzyme and electrode. SAMs formed from hydrophilic charged thiols achieved nearly two times higher current densities compared to hydrophobic charged thiols. Additionally, the results also indicated proportionality between HiCDH catalytic constant and water content of the enzyme film. Enzyme films on charged pyridine thiols had smaller variations in water content and viscoelastic properties than films adsorbed on the more hydrophobic thiols. This work highlights several perspectives on the underlying factors affecting performance of immobilized HiCDH. (C) 2017 Elsevier B.V. All rights reserved.
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| 2. |
- Misiunas, A., et al.
(författare)
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Thermomyces lanuginosus lipase in the liquid-crystalline phases of aqueous phytantriol: X-ray diffraction and vibrational spectroscopic studies
- 2008
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Ingår i: Biophysical Chemistry. - : Elsevier BV. - 1873-4200 .- 0301-4622. ; 134:3, s. 144-156
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Tidskriftsartikel (refereegranskat)abstract
- The influence of Thermomyces lanuginosus lipase (TLL) on the phase behaviour of liquid-crystalline phases of aqueous phytantriol as well as conformational changes of TLL entrapped in the cubic Q(230) phase have been studied by small angle X-ray diffraction (SAXD), FT-Raman, and FT-IR techniques. It was found that the lipidic Q(230) Phase is able to accommodate up to 10 wt.% of TLL, and the temperature of phase transition to the inverted hexagonal phase H-11 increases indicating stabilizing effect of the protein. FT-Raman analysis of Trp amino acid marker band W3 revealed that the average rotation angle around the C-3 - C-beta bond of four TLL residues of TLL in the Q(230) phase increases. Reasoning from available TLL crystallographic data, this result is explained by structural transition of entrapped protein to so-called "open" and more related to the enzymaticallyactive conformation. TLL secondary structure analysis by amide I and amide III vibrational bands showed that content of alpha-helixes does not change, while a part of beta-sheet structures transforms to less ordered elements upon incorporation of protein into the Q230 phase of aqueous phytantriol. (c) 2008 Elsevier B.V. All rights served.
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| 3. |
- Talaikyte, Z, et al.
(författare)
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Interactions of cyclic AMP and its dibutyryl analogue with a lipid layer in the aqueous mixtures of monoolein preparation and dioleoyl phosphatidylcholine as probed by X-ray diffraction and Raman spectroscopy
- 2004
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Ingår i: Journal of Biological Physics. - 0092-0606. ; 30:1, s. 83-96
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Tidskriftsartikel (refereegranskat)abstract
- Interactions of adenosine 3':5'-cyclic monophosphate (cAMP) and N-6,2'-O-dibutyryl-adenosine 3':5'-cyclic monophosphate (dbcAMP) with a lipid layer composed of monoolein-based preparation and dioleoyl phosphatidylcholine ( DOPC) were investigated by small-angle X-ray diffraction (SAXD) and Raman spectroscopy. The reversed hexagonal (H-II) MO/DOPC/H2O phase of 65:15:20 wt.% composition was selected as a reference system. SAXD revealed that entrapment (at the expense of water) of 3 wt.% cAMP into the reference system did not change the polymorphic form and structural parameters of the phase. The same content of dbcAMP induced the transition from the HII phase to the reversed bicontinuous cubic phase of space group Ia3d. This transition is explained by the increase of lipid head-group area due to the penetration of the acylated adenine group of dbcAMP into the polar/apolar region of lipid layer. The conclusion is supported by Raman spectroscopy, showing the disruption/weakening of hydrogen bonding in the MO/DOPC-based matrix at the N1- and N3-sites of the dbcAMP adenine ring. As distinct from dbcAMP, cAMP remains mostly in the water channels of the HII phase, although the phosphate residue of nucleotide interacts with the quaternary ammonium group of DOPC. Both nucleotides increase the population of gauche isomers in the DOPC choline group.
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