Alcohol and polyol dehydrogenases

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• Two main groups of alcohol dehydrogenases exist: "long" and "short" forms, differing in structure and catalytic mechanisms.
• These classifications also appear applicable to polyol dehydrogenases.
• Mammalian liver sorbitol dehydrogenase exhibits structural characteristics intermediate between mammalian and yeast alcohol dehydrogenases.

Purpose of the Study:

• To determine the N-terminal amino acid sequence of mammalian liver sorbitol dehydrogenase.
• To compare this sequence with known alcohol dehydrogenases to establish evolutionary and functional relationships.

Main Methods:

• Amino acid sequencing of the N-terminal region of liver sorbitol dehydrogenase.
• Comparative sequence analysis against databases of alcohol and polyol dehydrogenases.

Main Results:

• The determined N-terminal amino acid sequence of liver sorbitol dehydrogenase is strictly homologous to "long" alcohol dehydrogenases.
• Seventeen conserved residues were identified across compared enzymes, indicating functional importance.
• Specific residues (proline, glycine, cysteine, histidine) suggest conserved structural and active site features, including a zinc atom.

Conclusions:

• Mammalian liver sorbitol dehydrogenase belongs to the "long" alcohol dehydrogenase family.
• The N-terminal sequence homology highlights conserved structural and functional elements critical for enzyme activity.
• This finding refines the understanding of dehydrogenase enzyme classification and evolution.