, Volume 31, Issue 11-12, pp 497-506

Characterization of mutation-induced changes in the maize (Zea mays L.) ADH1-1S1108 alcohol dehydrogenase

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The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.

Funding for this research was from a University of Nebraska—Lincoln Research Council Grant-in-Aid and from the UNL Center for Biotechnology. Sequencing was carried out by the UNL Center for Biotechnology Core Facility for DNA Sequencing. Computing costs were supported by the UNL Computer Resource Center.
The sequence forAdh1-1S1108 is available as Gen-Bank accession L23548.