1A71

TERNARY COMPLEX OF AN ACTIVE SITE DOUBLE MUTANT OF HORSE LIVER ALCOHOL DEHYDROGENASE, PHE93=>TRP, VAL203=>ALA WITH NAD AND TRIFLUOROETHANOL


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.199 

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This is version 1.2 of the entry. See complete history


Literature

Active site modifications in a double mutant of liver alcohol dehydrogenase: structural studies of two enzyme-ligand complexes.

Colby, T.D.Bahnson, B.J.Chin, J.K.Klinman, J.P.Goldstein, B.M.

(1998) Biochemistry 37: 9295-9304

  • DOI: 10.1021/bi973184b
  • Primary Citation of Related Structures:  
    1A71, 1A72

  • PubMed Abstract: 
  • The oxidation of alcohol to aldehyde by horse liver alcohol dehydrogenase (LADH) requires the transfer of a hydride ion from the alcohol substrate to the cofactor nicotinamide adenine dinucleotide (NAD). A quantum mechanical tunneling contribution to this hydride transfer step has been demonstrated in a number of LADH mutants designed to enhance or diminish this effect [Bahnson, B ...

    The oxidation of alcohol to aldehyde by horse liver alcohol dehydrogenase (LADH) requires the transfer of a hydride ion from the alcohol substrate to the cofactor nicotinamide adenine dinucleotide (NAD). A quantum mechanical tunneling contribution to this hydride transfer step has been demonstrated in a number of LADH mutants designed to enhance or diminish this effect [Bahnson, B. J., et al. (1997) Proc. Natl. Acad. Sci. U.S.A. 94, 12797-12802]. The active site double mutant Phe93 --> Trp/Val203 --> Ala shows a 75-fold reduction in catalytic efficiency relative to that of the native enzyme, and reduced tunneling relative to that of either single mutant. We present here two crystal structures of the double mutant: a 2.0 A complex with NAD and the substrate analogue trifluoroethanol and a 2.6 A complex with the isosteric NAD analogue CPAD and ethanol. Changes at the active site observed in both complexes are consistent with reduced activity and tunneling. The NAD-trifluoroethanol complex crystallizes in the closed conformation characteristic of the active enzyme. However, the NAD nicotinamide ring rotates away from the substrate, toward the space vacated by replacement of Val203 with the smaller alanine. Replacement of Phe93 with the larger tryptophan also produces unfavorable steric contacts with the nicotinamide carboxamide group, potentially destabilizing hydrogen bonds required to maintain the closed conformation. These contacts are relieved in the second complex by rotation of the CPAD pyridine ring into an unusual syn orientation. The resulting loss of the carboxamide hydrogen bonds produces an open conformation characteristic of the apoenzyme.


    Related Citations: 
    • A Link between Protein Structure and Enzyme Catalyzed Hydrogen Tunneling
      Bahnson, B.J., Colby, T.D., Chin, J.K., Goldstein, B.M., Klinman, J.P.
      (1997) Proc Natl Acad Sci U S A 94: 12797

    Organizational Affiliation

    Department of Biochemistry and Biophysics, University of Rochester Medical Center, New York 14642, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
LIVER ALCOHOL DEHYDROGENASEA, B374Equus caballusMutation(s): 2 
Gene Names: LADH F93W V203A
EC: 1.1.1.1
UniProt
Find proteins for P00327 (Equus caballus)
Explore P00327 
Go to UniProtKB:  P00327
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.199 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.6α = 103
b = 44.1β = 87.9
c = 92.6γ = 70.7
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

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Ligand Structure Quality Assessment  



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-06-17
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance