Sequences of B.sub.12-dependent dehydratases with improved reaction kinetics are presented. Use of these B.sub.12-dependent dehydratases reduce the rate of the enzyme's suicide inactivation in the presence of glycerol and 1,3-propanediol. The enzymes were created using error-prone PCR and oligonucleotide-directed mutagenesis to target the DhaB1 gene, which encodes the .alpha.-subunit of glycerol dehydratase. Mutants with improved reaction kinetics were rapidly identified using high throughput assays.