Stability/activity tradeoffs in Thermusthermophilus HB27 laccase.

ABSTRACT: We report the temperature dependence of the formal potential of type 1 copper (Cu_T1) in Thermusthermophilus HB27 laccase. Employing [Ru(NH₃)₄(bpy)](PF₆)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 ΔS_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 f

SUBMITTER: Shin J 

PROVIDER: S-EPMC7085441 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature