>gnl|CDD|176221 cd08260, Zn_ADH6, Alcohol dehydrogenases of the MDR family. NAD(P)(H)-dependent oxidoreductases are the major enzymes in the interconversion of alcohols and aldehydes, or ketones. This group has the characteristic catalytic and structural zinc sites of the zinc-dependent alcohol dehydrogenases. Alcohol dehydrogenase in the liver converts ethanol and NAD+ to acetaldehyde and NADH, while in yeast and some other microorganisms ADH catalyzes the conversion acetaldehyde to ethanol in alcoholic fermentation. ADH is a member of the medium chain alcohol dehydrogenase family (MDR), which has a NAD(P)(H)-binding domain in a Rossmann fold of a beta-alpha form. The NAD(H)-binding region is comprised of 2 structurally similar halves, each of which contacts a mononucleotide. A GxGxxG motif after the first mononucleotide contact half allows the close contact of the coenzyme with the ADH backbone. The N-terminal catalytic domain has a distant homology to GroES. These proteins typically form dimers (typically higher plants, mammals) or tetramers (yeast, bacteria), and have 2 tightly bound zinc atoms per subunit, a catalytic zinc at the active site and a structural zinc in a lobe of the catalytic domain. NAD(H)-binding occurs in the cleft between the catalytic and coenzyme-binding domains at the active site, and coenzyme binding induces a conformational closing of this cleft. Coenzyme binding typically precedes and contributes to substrate binding. In human ADH catalysis, the zinc ion helps coordinate the alcohol, followed by deprotonation of a histidine, the ribose of NAD, a serine, then the alcohol, which allows the transfer of a hydride to NAD+, creating NADH and a zinc-bound aldehyde or ketone. In yeast and some bacteria, the active site zinc binds an aldehyde, polarizing it, and leading to the reverse reaction. Length = 345

 Score =  110 bits (278), Expect = 5e-25
 Identities = 76/296 (25%), Positives = 129/296 (43%), Gaps = 39/296 (13%)

Query: 7   MRHVAMSGYGKSNVMFLAESPIPQPQKEEILIKVEAIGVNRPDVMQRKGLYPPPKNANP- 65
           MR      +G+   + + E P P+P  + ++++VEA GV R D    +G    P    P 
Sbjct: 1   MRAAVYEEFGE--PLEIREVPDPEPPPDGVVVEVEACGVCRSDWHGWQG--HDPDVTLPH 56

Query: 66  ILGLEVAGKIVDLGENTTHWNIGDEVCA---LVNG------------------------G 98
           + G E AG +V++GE+ + W +GD V     L  G                        G
Sbjct: 57  VPGHEFAGVVVEVGEDVSRWRVGDRVTVPFVLGCGTCPYCRAGDSNVCEHQVQPGFTHPG 116

Query: 99  GYAEYCLSHQG-HTL-PIPKGYNAIQAASLPESFFTVWANLFQTANLRSGQTVLIHGGSS 156
            +AEY    +    L  +P   + + AA L   F T +  L   A ++ G+ V +HG   
Sbjct: 117 SFAEYVAVPRADVNLVRLPDDVDFVTAAGLGCRFATAFRALVHQARVKPGEWVAVHGC-G 175

Query: 157 GIGTTAIQLASYFGATVYTTAKSEEKCLACLKLGAKHAINY-LKEDFLEILQKETQGRGI 215
           G+G +A+ +AS  GA V      ++K     +LGA   +N    ED    ++  T G G 
Sbjct: 176 GVGLSAVMIASALGARVIAVDIDDDKLELARELGAVATVNASEVEDVAAAVRDLTGG-GA 234

Query: 216 DIILDMVG-AEYLNQHLTLLSKEGKLIIIS-FLGGNIATEINLNPIISKRITITGS 269
            + +D +G  E     +  L K G+ + +   LG      + ++ ++++ + I GS
Sbjct: 235 HVSVDALGIPETCRNSVASLRKRGRHVQVGLTLGEEAGVALPMDRVVARELEIVGS 290