Stability/activity tradeoffs in Thermusthermophilus HB27 laccase

We report the temperature dependence of the formal potential of type 1 copper (Cu T1 ) in Thermus thermophilus HB27 laccase. Employing [Ru(NH 3 ) 4 (bpy)](PF 6 ) 2 (0.505 vs. NHE) as the redox titrant, we found that the Cu T1 2+/+ potential decreased from approximately 480 to 420 mV (vs. NHE) as the...

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Bibliographic Details
Published in:Journal of biological inorganic chemistry 2020-03, Vol.25 (2), p.233-238
Main Authors: Shin, Jieun, Gray, Harry B., Winkler, Jay R.
Format: Article
Language:English
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Summary:We report the temperature dependence of the formal potential of type 1 copper (Cu T1 ) in Thermus thermophilus HB27 laccase. Employing [Ru(NH 3 ) 4 (bpy)](PF 6 ) 2 (0.505 vs. NHE) as the redox titrant, we found that the Cu T1 2+/+ potential decreased from approximately 480 to 420 mV (vs. NHE) as the temperature was raised from 20 to 65 °C. Of importance is that the Δ S rc ° of − 120 J mol −1  K −1 is substantially more negative than those for other blue copper proteins. We suggest that the highly unfavorable reduction entropy is attributable to Cu T1 inaccessibility to the aqueous medium. Although the active site residues are buried, which is critical for maintaining thermostability, the flexibility around Cu T1 is maintained, allowing enzyme activity at ambient temperature
ISSN:0949-8257
1432-1327
DOI:10.1007/s00775-020-01754-7