Biocatalyst activity in nonaqueous environments correlates with centisecond-range protein motions

Ross K. Eppler, Elton P. Hudson, Shannon D. Chase, Jonathan S. Dordick, Jeffrey A. Reimer, and Douglas S. Clark
PNAS October 14, 2008 105 (41) 15672-15677; https://doi.org/10.1073/pnas.0804566105

  1. Edited by Alexander M. Klibanov, Massachusetts Institute of Technology, Cambridge, MA, and approved August 26, 2008 (received for review June 2, 2008)

Article Figures & SI

Figures

  • Fig. 1.
    Fig. 1.

    Catalytic efficiency kcat/Km (s−1·M−1) in hexane of SC biocatalysts containing different weight fractions of sodium fluoride.

  • Fig. 2.
    Fig. 2.

    Entropic (TΔΔS†, T = 303 K) and enthalpic (ΔΔH†) contributions to catalysis for salt-activated SC. (A) NaF-activated SC in hexane and in acetone. (B) Ninety-eight percent (wt/wt) salt-activated SC in hexane as a function of Δ Jones–Dole B coefficient (20). Biocatalysts from left to right: 98% (wt/wt) NaCl, 98% (wt/wt) NaF, 98% (wt/wt) KCl, 98% (wt/wt) KF, and 98% (wt/wt) KHCO3.

  • Fig. 3.
    Fig. 3.

    1H MAS NMR relaxation studies of SC biocatalysts in hexane. (A) Total range of biocatalyst turnover numbers. (B) Expansion of low-activity regime: T1zzH (filled triangles), T1ρH (open circles), and T1H (open squares). From left to right: salt-free, 50% (wt/wt) NaF, 75% (wt/wt) NaF, 85% (wt/wt) NaF, 98% (wt/wt) NaCl, 98% (wt/wt) NaF, 98% (wt/wt) KF, and 98% (wt/wt) KCl.

  • Fig. 4.
    Fig. 4.

    19F NMR chemical shift measurements of 4-fluorobenzylsulfonyl chloride (4-FBSCI) in solvents of varying dielectric constant. Solvents, from left to right: n-hexane (ε = 1.9), isooctane (ε = 2.2), THF (ε = 7.8), CH3Cl (ε = 9.1), acetone (ε = 20.7), methanol (ε = 32.7), DMF (ε = 36.7), and DMSO (ε = 46.5).

  • Fig. 5.
    Fig. 5.

    19F NMR chemical shift measurements of 4-FBS-SC in hexane. From left to right: salt-free, 50% (wt/wt) NaF, 75% (wt/wt) NaF, 85% (wt/wt) NaF, 98% (wt/wt) NaCl, 98% (wt/wt) NaF, 98% (wt/wt) KF, and 98% (wt/wt) KCl.

  • Fig. 6.
    Fig. 6.

    Experimental (black) and simulated (gray) ESR spectra of salt-activated 4-FBS-SC in hexane: line A, 98% (wt/wt) KF; line B, 98% (wt/wt) KCl; line C, 98% (wt/wt) NaF; line D, 98% (wt/wt) NaCl; line E, 85% (wt/wt) NaF; line F, 75% (wt/wt) NaF; line G, 50% (wt/wt) NaF; line H, salt-free.

  • Fig. 7.
    Fig. 7.

    ESR simulation parameters for SC biocatalysts.

Tables

  • Table 1.

    ESR simulation parameters for SC biocatalysts

    Conditionskcat/Km, s−1·M−1% faster populationτc fast, τcslow, nsA0, G
    Salt-free0.092——, 6.61—, 16.8
    50% (wt/wt) NaF2.12——, 8.51—, 16.4
    75% (wt/wt) NaF14.50.060.71, 8.3215.9, 16.3
    85% (wt/wt) NaF19.00.150.76, 6.2215.9, 16.4
    98% (wt/wt) NaCl30.50.140.89, 7.5915.9, 16.3
    98% (wt/wt) NaF76.80.240.78, 6.3515.9, 16.1
    98% (wt/wt) KCl2000.240.78, 6.3715.9, 16.1
    98% (wt/wt) KF2480.410.64, 1.8616.2, 15.3
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Biocatalyst activity in nonaqueous environments correlates with centisecond-range protein motions
Ross K. Eppler, Elton P. Hudson, Shannon D. Chase, Jonathan S. Dordick, Jeffrey A. Reimer, Douglas S. Clark
Proceedings of the National Academy of Sciences Oct 2008, 105 (41) 15672-15677; DOI: 10.1073/pnas.0804566105
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