Diaminopelargonic acid

Alanine also gives rise to a precursor of the vitamin biotin (Eq. 24-39) after a PFP-dependent decar-boxylative condensation with the 7-carbon dicarbox-ylic acid unit of pimeloyl-CoA in a reaction analogous to that of Eq. 14-32.351 The resulting alcohol is reduced to 7-oxo-8-aminopelargonic acid which is converted by transamination, with S-adenosylmethionine as the nitrogen donor,351a to 7,8-diaminopelargonic acid. 

Completion of the ureido ring of biotin, yielding detbiobiotin, is by a car-boxylation reaction using CO2 and ATP. The reaction proceeds by the formation of a monocarbamate by reaction between diaminopelargonic acid and CO2, followed by formation of a substimted carbamyl phosphate, which then... 

Figure 11.3. Biosynthesis of biotin. Keto-aminopelargonic acid synthase, EC 2.3.1.47 diaminopelargonic acid synthase (aminotransferase), EC 2.6.1.62 dethiobiotin synthase, EC 6.3.3.3 and biotin synthase, EC 2.8.1.6.

Diaminopelargonic acid [172] E. coli S-Adenosyl-2-oxomethyl- thiobutyrate... 

Then the 7,8-diaminononanoate (7,8-diaminopelargonic acid) (Scheme 12.93) is converted to the bisamide dethiobiotin (an imidazolidone) by carboxylation with carbon dioxide (CO2) in the presence of ATP in a reaction requiring magnesium (Mg+ ) and catalyzed by dethiobiotin synthase (EC 6.3.3.3). The well-known reversible reaction of amines with carbon dioxide (CO2) and an X-ray crystal structure showing the 8-amino group as a mixed carbonic phosphate anhydride has lent support to this picture (PDB la82). Finally, in the presence of biotin synthase (EC 2.8.1.6), an enzyme that appears to be used only once in each synthesis, reaction occurs with 2 equivalents (but almost certainly one at a time) of SAM and sulfur to produce biotin, 2 equivalents of methionine (Met, M), and 2 equivalents of 5 -deoxyadenosine. 

Cyclic five-membered ring urethane derivatives are also available, and they serve as precursors to amino acids. In one specialized synthesis, dethio-biotin(2,/7 was treated with hot HCl to give 7,8-diaminononanoic acid (7,8-diaminopelargonic acid,... 

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