0000000000006482
AUTHOR
Janne Savolainen
Introduction of histidine residues into avidin subunit interfaces allows pH-dependent regulation of quaternary structure and biotin binding
AbstractIn order to turn the subunit association and biotin binding of avidin into pH-sensitive phenomena, we have replaced individually three amino acid residues in avidin (Met96, Val115 and Ile117) with histidines in the 1–3 interface, and in combination with a histidine conversion in the 1–2 interface (Trp110). The single replacements Met96His and Val115His in the 1–3 interface were found to have a clear effect on the quaternary structure of avidin, since subunit associations of these mutants became pH-dependent. The histidine replacement in the 1–2 interface affected the biotin-binding properties of the mutants, in particular reversibility of binding and protein–ligand complex formation…
Characterization of poultry egg-white avidins and their potential as a tool in pretargeting cancer treatment.
Chicken avidin and bacterial streptavidin are proteins used in a wide variety of applications in the life sciences due to their strong affinity for biotin. A new and promising use for them is in medical pretargeting cancer treatments. However, their pharmacokinetics and immunological properties are not always optimal, thereby limiting their use in these applications. To search for potentially beneficial new candidates, we screened egg white from four different poultry species for avidin. Avidin proteins, isolated from the duck, goose, ostrich and turkey, showed a similar tetrameric structure, similar glycosylation and stability against both temperature and proteolytic activity of proteinase…
A divided country : microhistorical perspective to the presidents and authority in Uganda
Tämän tutkimuksen tarkoituksena on tarkastella Ugandan yhteiskunnan kehitystä kahden eri kysymyksen kautta: Kuinka pohjoisen ja etelän jako on kehittynyt itsenäisyyden aikana sekä millainen on acholi-heimon asema Ugandan politiikassa? Tutkimus kuvaa narratiivien avulla eri presidenttien valtakausia sekä näiden kahden ilmiön kehitystä. Metodologisesti tutkimus hyödyntää mikrohistorian muunnelmaa yhdessä Max Weberin auktoriteettikäsitteiden sekä Christopher Claphamin mukaisen uus-patrimonialismin käsitteen kanssa. Kysymysten tarkastelu on jaettu jaksoihin, jotka vastaavat Ugandan presidenttien virkakausia. Tutkimuksen päämateriaali koostuu poliittisista elämänkerroista ja kirjallisuusmateriaa…
Femtosecond Transient Absorption Study of the Dynamics of Acrylodan in Solution and Attached to Human Serum Albumin
The excited-state relaxation dynamics of the protein-labeling dye acrylodan in solution and attached to human serum albumin has been studied by femtosecond transient absorption spectroscopy. Time-resolved spectra and kinetics of stimulated emission and excited-state absorption in the wavelength region from 400 to 800 nm were studied in ethanol and dimethylformamide. The excited-state solvation dynamics is characterized by multiexponential behavior in both solvents. In ethanol solution, the time dependence of the transient spectra is interpreted in terms of fast solvent relaxation followed by excited-state isomerization of the dye. Acrylodan attached to the protein shows a relaxation compone…