R -A Leucine

The presence of B12-dependent leucine 2,3-aminomutases in bacteria, mammals, and plants has also been reported [44-46]. Their existence was deduced only indirectly. B12 itself has not yet been detected in plants, however. Later Stabler [47] and Aberhart [48] reported independently they were unable to detect / -leucine and leucine 2,3-aminomutase activity in human blood and rat liver. The presence in these of B12-dependent leucine 2,3-aminomutases is therefore questionable. 

Although there are no reports of isolation of the enzyme and its cofactor requirements, the involvement of cobalamin seems unlikely, because it is generally accepted that plants do not contain Bi2. 

Biosynthesis of (R)-/f-Phenylalanine in Taxus baccata The biosynthesis of the (R)-3-(dimethylamino)-3-phenylpropionic acid (Wintersteirfs acid) moiety of taxine A [56] and taxine B [57] in Taxus baccata has been reported by Haslam and coworkers [58]. They investigated whether /(-phenylalanine is generated by an aminomutase 

Biosynthesis of (S)-/ -Tyrosine in Bacillus brevis Vm4 //-Tyrosine 43 is a constituent of the peptide antibiotics edeine A and B [60] obtained from cultures of BaciUus brevis Vm4. //-Tyrosine is derived from a-tyrosine 42 by use of a tyrosine 2,3-aminomutase [61]. The purified enzyme has properties fundamentally different from those of all other aminomutases so far mentioned. It requires ATP and Mg2+ ions, but no other cofactors. 

Biosynthesis of (R)-/J-Tyrosine and (R)-/f-Dopa in Cortinarius violaceus Fruit bodies of the higher fungus Cortinarius violaceus produce (R)-/ -dopa 44 [63], The biosyn- 

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