1d1s
From Proteopedia
WILD-TYPE HUMAN SIGMA (CLASS IV) ALCOHOL DEHYDROGENASE
Structural highlights
Function[ADH7_HUMAN] Could function in retinol oxidation for the synthesis of retinoic acid, a hormone important for cellular differentiation. Medium-chain (octanol) and aromatic (m-nitrobenzaldehyde) compounds are the best substrates. Ethanol is not a good substrate but at the high ethanol concentrations reached in the digestive tract, it plays a role in the ethanol oxidation and contributes to the first pass ethanol metabolism. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPyrazole and its 4-alkyl substituted derivatives are potent inhibitors for many alcohol dehydrogenases. However, the human sigma sigma isoenzyme exhibits a 580-fold lower affinity for 4-methylpyrazole than does the human beta1beta1 isoenzyme, with which it shares 69% sequence identity. In this study, structural and kinetic studies were utilized in an effort to identify key structural features that affect the binding of 4-methylpyrazole in human alcohol dehydrogenase isoenzymes. We have extended the resolution of the human sigma sigma alcohol dehydrogenase (ADH) isoenzyme to 2.5 A resolution. Comparison of this structure to the human beta1beta1 isoenzyme structure indicated that the side-chain position for Met141 in sigma sigma ADH might interfere with 4-methylpyrazole binding. Mutation of Met141 in sigma sigma ADH to Leu (sigma141L) lowers the Ki for 4-methylpyrazole from 350 to 10 microM, while having a much smaller effect on the Ki for pyrazole. Thus, the mutagenesis results show that the residue at position 141, which lines the substrate-binding pocket at a position close to the methyl group of 4-methylpyrazole, directly affects the binding of the inhibitor. To rule out nonspecific structural changes due to the mutation, the X-ray structure of the sigma141L mutant enzyme was determined to 2.4 A resolution. The three-dimensional structure of the mutant enzyme is identical to the wild-type enzyme, with the exception of the residue at position 141. Thus, the differences in 4-methylpyrazole binding between the mutant and wild-type sigma sigma ADH isoenzymes can be completely ascribed to the local changes in the topology of the substrate binding site, and provides an explanation for the class-specific differences in 4-methylpyrazole binding to the human ADH isoenzymes. Methionine-141 directly influences the binding of 4-methylpyrazole in human sigma sigma alcohol dehydrogenase.,Xie PT, Hurley TD Protein Sci. 1999 Dec;8(12):2639-44. PMID:10631979[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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