To obtain the subject new protein consisting of a protein having a specific amino acid sequence, to be used for producing L-aspartic acid useful as e.g. a medicine, food additive, surfactant, raw material for biodegradable chelating agents.

This new protein, which has aspartase activity, has an amino acid sequence of the formula where, optionally, amino acid(s) are deleted, substituted or added, and is used for producing L-aspartic acid useful as e.g. a medicine, food additive, surfactant, raw material for biodegradable chelating agents from fumaric acid and ammonia. This new protein is obtained by the following process: a DNA is isolated from Rhodococcus sp. EA4 (FERM P-12136), a DNA library is made using the above DNA by conventional means, and then screened using an aspartase gene fragment as probe, and the resulting aspartase gene is integrated into a vector and expressed in host cells.