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Both species of broomrape tested were devoid of L-threonine dehydratase and L-serine dehydratase activity. When the seeds of three species of dodder were examined, threonine dehydratase activity was present in two but absent in the third, The enzyme could also not be demonstrated in the seed of a green mistletoe. Absence of threonine/serine dehydratase may be a factor necessitating or associated with the parasitic existence of broomrape. The significance of the presence of threonine dehydratase in some seeds and absence in some others is briefly discussed. [ABSTRACT FROM AUTHOR]

α-Mercapto-β-(2-furyl) acrylic acid (MFA), α-mercapto-β-(2-hydroxyphenyl) acrylic acid (MHA), β-1,2-phenylene di-α-mercaptoacrylic acid (1,2-PDMA) and β-1,4-phenylene di-α-mercapto acrylic acid (1,4-PDMA) were compared to sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC) an effective cadmium chelator, for their ability to mobilize Cd and influence the Cd induced tissue metallothionein (MT) in rats administered 100CdCl2, 72 hr earlier. MFA was almost as effective as NBG-DTC but more effective than MHA in enhancing urinary and faecal excretion of Cd, reducing tissue and blood levels of Cd and in lowering Cd induced increase in hepatic and renal MT contents. 1,2-PDMA and 1,4-PDMA were effective only in reducing the hepatic burden of Cd. The resuls do not indicate any direct relationship between the efficacy of α-mercapto-β-aryl acrylic acids to decorporate body Cd and their lipophilic-hydrophilic character or number-arrangement of their sulfhydryl groups. [ABSTRACT FROM AUTHOR]

α-Mercapto-β-(2-furyl) acrylic acid (MFA), α-mercapto-β-(phenyl) acrylic acid (MPA), α-mercapto-β-(2-hydroxyphenyl) acrylic acid (MHA), α-mercapto-β-(4-methoxyphenyl) acrylic acid (MMA), β-1,2-phenylene di-α-mercapto acrylic acid (1, 2-PDMA) and β-1, 4-phenylene di-α-mercapto acrylic acid (1, 4-PDMA) enhanced faecal excretion and reduced liver, spleen and blood burden of inorganic mercury when administered (0.5 m mol/kg, in two split doses) 24 hr after Hg (II) (1 mg/kg) in rats. MFA, MPA, MHA and MMA were also effective in lowering renal Hg mainly from the cytosol, without any significant increase in urinary excretion of Hg. The results indicate that all the mono-mercapto acrylic acids including MFA were more effective than di-mercapto acrylic acids and act through the mechanism characteristic of thiol chelators, that is, mobilization of Hg as their complexes, contrary to the reported observation that MFA acts through the induction of metallothionein. [ABSTRACT FROM AUTHOR]