Mimosine.synthase

Fig. 231. Biosynthesis of mimosine 1 Mimosine synthase 2 mimosine glucosyltransferase...

In addition to compounds related to mimosine, other NPAAs are synthesized by transfer of an alanine residue catalysed by cysteine synthase, e.g. the formation of isoxazolin-5-on-2-yl-alanine in Lathyrus sativus (Ikegami et al, 1993). Moreover, partial purification of cysteine synthase from Allium tuberosum revealed that this enzyme also catalyses the formation of cysteine derivatives, such as S-allylcysteine (Ikegami et al, 1993). The various aspects of the formation of NPAAs by cysteine synthase are presented by Noji et al. (1993) and Ikegami and Murakoshi (1994). 

Ikegami, R, Mizuno, M. and Murakoshi, I. (1990) Enzymatic synthesis of the thyrotoxic amino acid, mimosine, by cysteine synthase. Phytochemistry, 29,3461-6. 

Activity toxicity M. is a powerful inhibitor of cystathionine synthase and cystathionase. The growth of shoots of Phaseolus aureus is inhibited by 3,4-dihy-droxypyridine and mimosine with equal activity. The inhibitory activity is neutralised by addition of pyri-doxal phosphate. M. causes loss of hair in sheep, horses, and pigs goats and cattle, in contrast, are not affected in this way. M. effects growing hair, impairs the estrogen cycle in rats, and DNA synthesis. ... 

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