Transaminases phenylethylamine transaminase

Deamination, Transamination. Two kiads of deamination that have been observed are hydrolytic, eg, the conversion of L-tyrosiae to 4-hydroxyphenyUactic acid ia 90% yield (86), and oxidative (12,87,88), eg, isoguanine to xanthine and formycia A to formycia B. Transaminases have been developed as biocatalysts for the synthetic production of chiral amines and the resolution of racemic amines (89). The reaction possibiUties are illustrated for the stereospecific synthesis of (T)-a-phenylethylamine [98-84-0] (ee of 99%) (40) from (41) by an (5)-aminotransferase or by the resolution of the racemic amine (42) by an (R)-aminotransferase. 

Dealing with substrate inhibition caused by application of higher amounts of reachon educts needs further investigahons in terms of ideal reaction conditions and amino donor/acceptor ratio. One crucial step for successful transamination is the choice of a suitable amino donor. Fesko et al. evaluated the influence of several amino donors and substrates to investigate a one-enzyme system [41], The influence of the amino donor on the ee was shown by examination of reactions catalyzed by the co-transaminase from Paracoccus denitrificans. Usually low ee values were obtained with alanine as the amino donor. The best results were acquired with l-phenoxy-2-propanone and 1-phenylethylamine in sodium phosphate buffer pH 7.5 at 30 °C. To get higher substrate loading, it is necessary to add cosolvents due to the low solubility of the substrates. In this study, cyclohexane and sodium dodecyl sulfate (SDS) were best cosolvents. For the preparation of (R)- and (S)-phenoxypropane-2-amine in a similar yield, three enzymes were used for the synthesis [66] rac-2-butylamine as amino donor usage was increased by tenfold (500 mM). 

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