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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Published in: | Journal of biological inorganic chemistry 2020-03, Vol.25 (2), p.233-238 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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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 |
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ISSN: | 0949-8257 1432-1327 |
DOI: | 10.1007/s00775-020-01754-7 |