Cloning of the aspartate-β-semialdehyde dehydrogenase structural gene fromEscherichia coli K12

Transformation ofEscherichia coli strains with the recombinant plasmid, prepared by “shot gun cloning” with pBR322 and containing the geneasd, the structural gene of aspartate-β-semialdehyde dehydrogenase, results in an increase in specific activity of 65-fold of the enzyme in crude extracts. Approximately 60 mg of pure enzyme may be obtained from 10 g of transformed cells (wet weight) in a simplified purification procedure. The molecular weight, amino acid composition, and kinetic properties of the enzyme appear to be the same as previously reported, and the first 36 amino acids of the N-terminal sequence have been determined.