S’-adenosyl-L-homocysteine AdoHcy

The enzyme converts erythromycin C into erythromycin A in the presence of AdoMet. Evidence was obtained that the enzyme is associated with the microsomal fraction. The enzyme showed a very high degree of substrate specificity. Aside from erythromycin C, it failed to catalyze the methylation of any other L-mycarosyl moiety tested. Erythromycin A and S-adenosyl-L-homocysteine (AdoHcy) were potent inhibitors of the enzyme, and it was assumed that the Ado-Met AdoHcy ratio could be a major regulatory factor of the final step in the formation of erythromycin A. 

The phosphonic aeid moiety has been shown to be inhibitors of numerous metabolic processes [99,100], In recent years, S-adenosyl-L-homocystein hydrolase(AdoHcy) has become an attractive target for drug design since its inhibitors have been shown to exhibit antiviral [101], antiparasitic [102], antiarthritic [103], and immunosuppressive effects [104], Importantly, a-aminophosphonate diesters are more attractive as intermediates for multistep synthesis than the corresponding phosphonic acids. The insolubility of the latter in both organic and neutral aqueous media complicates derivation of both the amine and acid functionalities. 

The following abbreviations are used AdoMet, ( )-S-adenosyl-L-methionine (formerly designated (-)- -adenosyl-L-methionine AdoHcy, -adenosyl-L-homocysteine. 

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