Temperature-dependent enantiospecificity of secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus

Pham, Van Thinh; Phillips, Robert S.; Ljungdahl, Lars G.

doi:10.1021/ja00187a089

Cited by 81 publications

(28 citation statements)

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“…The experimental findings obtained in the present study stress the importance of entropy in enzyme catalysis in general and in enantioselectivity in particular, as shown previously (Pham et al 1989; Phillips 1992; Galunsky et al 1997; Sakai et al 1997; Jönsson et al 1999; Overbeeke et al 1999; Ottosson and Hult 2001; Ottosson et al 2001). The five substrates in the present investigation all have entropic terms of differential activation free energy, TΔ R−S Δ S ‡ , that are 25% to 60% of the enthalpic term (Table 2).…”

Section: Discussionsupporting

confidence: 90%

“…As in several previous studies, we noted the importance of differential activation entropy in enzyme enantioselectivity (Pham et al 1989; Phillips 1992; Galunsky et al 1997; Sakai et al 1997; Jönsson et al 1999; Overbeeke et al 1999; Ottosson and Hult 2001; Ottosson et al 2001). The large contribution of differential activation entropy to enantioselectivity for 1‐bromo‐2‐butanol showed that steric factors alone could not explain the role of entropy in enantioselectivity.…”

Section: Discussionsupporting

confidence: 82%

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Substrate entropy in enzyme enantioselectivity: An experimental and molecular modeling study of a lipase

2002

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The temperature dependence of the enantioselectivity of Candida antarctica lipase B for 3-hexanol, 2-butanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, and 1-bromo-2-butanol revealed that the differential activation entropy, ⌬ R−S ⌬S ‡ , was as significant as the differential activation enthalpy, ⌬ R−S ⌬H ‡ , to the enantiomeric ratio, E. 1-Bromo-2-butanol, with isosteric substituents, displayed the largest ⌬ R−S ⌬S ‡ . 3-Hexanol displayed, contrary to other sec-alcohols, a positive ⌬ R−S ⌬S ‡ . In other words, for 3-hexanol the preferred R-enantiomer is not only favored by enthalpy but also by entropy. Molecular dynamics (MD) simulations and systematic search calculations of the substrate accessible volume within the active site revealed that the (R)-3-hexanol transition state (TS) accessed a larger volume within the active site than the (S)-3-hexanol TS. This correlates well with the higher TS entropy of (R)-3-hexanol. In addition, this enantiomer did also yield a higher number of allowed conformations, N, from the systematic search routines, than did the S-enantiomer. The substrate accessible volume was greater for the enantiomer preferred by entropy also for 2-butanol. For 3,3-dimethyl-2-butanol, however, neither MD-simulations nor systematic search calculations yielded substrate accessible volumes that correlate to TS entropy. Ambiguous results were achieved for 3-methyl-2-butanol.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 82%

Substrate entropy in enzyme enantioselectivity: An experimental and molecular modeling study of a lipase

2002

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“…In addition, biocatalysts from hyperthermophilic sources seem to be inherently more rigid, especially at suboptimal temperatures (15, 16), a characteristic that may be advantageous in applications involving chiral separations (17 − 19). Currently little is known about the potential of hyperthermophilic enzymes for this purpose, with one notable exception being with thermostable secondary dehydrogenases (20 − 23). To further investigate these issues, hyperthermophilic genome sequences were searched with a variety of bioinformatic tools for potential esterase homologues to Carboxylesterase NP and Candida rugosa lipase.…”

Section: Introductionmentioning

confidence: 99%

An unexpected plasticization phenomenon and a constant of the change rate of viscoelastic properties for polymers during nanoindentation test

Tang

Hou

Truss

et al. 2011

J of Applied Polymer Sci

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The effect of loading force, loading rate and unloading rate on the viscoelastic behavior of three representative polymers: poly(methyl methacrylate) (PMMA, amorphous polymer), polyvinylidene fluoride (PVDF, semicrystalline polymer), and epoxy (crosslinked polymer) have been investigated using nanoindentation. The results showed that the maximum indentation depth increased with the increase of loading force, and the relationship between loading force and depth became linear when the loading force is beyond 3000 lN. At the beginning, the plasticity index changed substantially with the increase of loading force, and after reaching a critical loading force, the plasticity index almost remained constant. The maximum indentation depth decreased with the increase of loading rate, which followed a power law curve. With the increase of loading rate, a plasticization phenomenon happened, and a possible reason is that the heat may accumulate and raise the local temperature. The plasticity index initially followed the power law with the increase of unloading rate and then almost remained constant. A constant, the change rate of viscoelastic properties with the unloading rate, for the three representative polymers studied in this research, around À0.033, has been obtained, which may be another manifestation of the phenomenon that many polymers have similar time/temperature shifts and that their WLF equation constants are approximately the same.

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“…These factors should consequently also influence the enantioselectivity of enzymes. Recently the first experimental data on its temperature dependence was published (Pham et al, 1989). The relative importance of substrate binding (Km) and catalytic reactions (kat) on the stereoselectivity was, however, not studied in detail.…”

Section: Introductionmentioning

confidence: 99%

The dependency of the stereoselectivity of penicillin amidases-enzymes with R-specific S1- and S-specific S?1-subsites- on temperature and primary structure

et al. 1996

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The stereoselectivity of penicillin amidase (PA, EC 3.51 .ll) from E co/i and homologeous enzymes from other sources has been determined as a function of temperature and substrate for hydrolysis and kinetically controlled synthesis. The stereoselectivity of these reactions decreased almost by one order of magnitude from 5 to 45°C. It increased with the substrate (kcat/Km) and nucleophile (e/h) specificity, and was found to differ in the Sl-(R-specific) and S,l -(S-specific)-binding subsites of the active site. The Sl -stereoselectivity was determined mainly by differences in the activation energy, i.e. the turnover number. The stereoselectivity of PA from different sources differed by almost an order of magnitude for the same substrate.

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Temperature-dependent enantiospecificity of secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus

Cited by 81 publications

References 0 publications

Substrate entropy in enzyme enantioselectivity: An experimental and molecular modeling study of a lipase

Substrate entropy in enzyme enantioselectivity: An experimental and molecular modeling study of a lipase

An unexpected plasticization phenomenon and a constant of the change rate of viscoelastic properties for polymers during nanoindentation test

The dependency of the stereoselectivity of penicillin amidases-enzymes with R-specific S1- and S-specific S?1-subsites- on temperature and primary structure

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