Biocatalysis for industrial production of fine chemicals.

Hydantoinases are valuable enzymes for the production of optically pure D- and L-amino acids. They catalyse the reversible hydrolytic ring cleavage of hydantoin or 5'-monosubstituted hydantoins and are therefore classified in the EC nomenclature as cyclic amidases (EC 3.5.2.). In the EC nomenclature, four different hydantoin-cleaving enzymes are described: dihydropyrimidinase (3.5.2.2), allantoinase (EC 3.5.2.5), carboxymethylhydantoinase (EC 3.5.2.4), and N-methylhydantoinase (EC 3.5.2.14). Beside these, other hydantoinases with known metabolic functions, such as imidase and carboxyethylhydantoinase and enzymes with unknown metabolic function, are described in the literature and have not yet been classified. An important question is whether the distinct hydantoinases, which are frequently classified as L-, D-, and non-selective hydantoinases depending on their substrate specificity and stereoselectivity, are related to each other. In order to investigate the evolutionary relationship, amino acid sequence data can be used for a phylogenetic analysis. Although most of these enzymes only share limited sequence homology (identity < 15%) and therefore are only distantly related, it can be shown (i) that most of them are members of a broad set of amidases with similarities to ureases and build a protein superfamily, whereas ATP-dependent hydantoinases are not related, (ii) that the urease-related amidases have evolved divergently from a common ancestor and (iii) that they share a metal-binding motif consisting of conserved histidine residues. The difference in enantioselectivity used for the classification of hydantoinases on the basis of their biotechnological value does not reflect their evolutionary relationship, which is to a more diverse group of enzymes than was assumed earlier. This protein superfamily probably has its origin in the prebiotic conditions of the primitive earth.

Microbial hydantoinases--industrial enzymes from the origin of life?

Substrate-dependent enantioselectivity of a novel hydantoinase from Arthrobacter aurescens DSM 3745 : Purification and characterization as new member of cyclic amidases

The purification and characterization of a novel D(−)-specific carbamoylase enzyme from an Agrobacterium sp.

Hydantoin racemase from Arthrobacter aurescens DSM 3747: heterologous expression, purification and characterization.

Cell growth and enzyme synthesis of a mutant of Arthrobacter sp. (DSM 3747) used for the production of L-amino acids from D,L-5-monosubstituted hydantoins.

Production of L-tryptophan from D,L-5-indolylmethylhydantoin by resting cells of a mutant of Arthrobacter species (DSM 3747).

Les hydantoines monosubstitues sont les substrats d'hydantoinases qui les transforment en D ou L carbanoyl-acides amines, lesquels sont transformes en D ou L acides amines par une carbamoylase. Une recherche de bacteries clivant stereospecifiquement les hydantoines est effectuee. Deux arthrobacters possedent des enzymes stereospecifiques: ce sont les Arthrobacter crystallopoietes AM2 et Arthrobacter spec. DSM 3747

Production of D- and L-amino acids from D,L-5-monosubstituted hydantoins

The invention relates to a process for the production of L-alpha-amino acids from 5-substituted hydantoins or N-carbamoyl-alpha-amino acids by biochemical reaction which is carried out with the aid of microorganisms or extracts obtained therefrom which contain the enzymes hydantoinase, D-L-carbamoyl-alpha-amino-acid racemase and L-N-carbamoyl-alpha-amino-acid amidohydrolase.

Christiane Gross

Papers

Cell growth and enzyme synthesis of a mutant of Arthrobacter sp. (DSM 3747) used for the production of L-amino acids from D,L-5-monosubstituted hydantoins.

Production of L-tryptophan from D,L-5-indolylmethylhydantoin by resting cells of a mutant of Arthrobacter species (DSM 3747).

Production of D- and L-amino acids from D,L-5-monosubstituted hydantoins

Process for the microbial production of L-alpha-amino acids