To investigate function and enzymatic characteristics of L-amino acid deaminase of Proteus mirabilis from acute pyelonephritis patients, L-amino acid deaminase encoding genes (pmzd1 and pmzd2) were cloned from P. mirabilis ZD1 and P. mirabilis ZD2 and nucleotide as well as amino acid sequences were analyzed. Prokaryotic expression system was established to express recombinant PMZD1 and PMZD2 and enzymatic characteristics were analyzed. Growth promotion tests were performed to establish the iron chelation and growth promotion effect of recombinant enzymes products. Results showed that recombinant PMZD1 and PMZD2 exhibited function of second type of L-amino acid deaminase but different in enzymatic characteristics, including affinity to substrates, reaction speed as well as optimal reaction temperature and pH, probably due to different amino acid sequences. Growth promotion tests indicated that products of the recombinant enzymes had growth promotion activities to P. mirabilis but exhibited no difference between the two enzymes.