The present invention relates to a hydantoinase having an amino acid sequence selected from (i) or (ii), with (i) amino acid sequence selected from SEQ ID NO: 6-20 and SEQ ID NO: 73-119 (ii) amino acid sequence wherein in the amino acid sequence of SEQ ID NO: 6-20 and SEQ ID NO: 73-119, 1 to 75 amino acid residues have been substituted, deleted, inserted and/or added, and wherein further the catalytic activity of the hydantoinase is higher by a factor of at least 1.2 than the catalytic activity of the hydantoinase having amino acid sequence SEQ ID NO: 1, The present invention further relates to a process for preparing amino acids, wherein said hydantoinase is used.