Production and Purification of d -Aminoacylase from Alcaligenes denitrificans and Taxonomic Study of the Strain

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Abstract
A d -aminoacylase-producing microorganism, strain DA181, isolated from soil was identified as Alcaligenes denitrificans subsp. denitrificans . This strain produced about 29,300 units (micromoles of product formed per hour) of d -aminoacylase and 2,300 units of l -aminoacylase per gram of cells (wet weight) when cultivated in a medium containing 1% N -acetyl- dl -leucine as the carbon source. The d -aminoacylase was purified 345-fold. The specific activity of the purified enzyme was 108,600 units per mg of protein when N -acetyl- d -methionine was used as a substrate. The apparent molecular weight was 58,000, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N -Acetyl- d -methionine was the favored substrate, followed by N -acetyl- d -phenylalanine. This enzyme had a high stereospecificity, and its hydrolysis of N -acetyl- l -amino acids was almost negligible.