Deoxyadenosine 3 -amino-3 -, crystal structure

Crystal structures of several 9-substituted adenines including 9-methyladenine (63AX907, 77AX(B)253), adenosine (72AX(B)1982), and 2 -deoxyadenosine (65AXiii) confirm the 6-amino structure. Additional references are given in a review (76AHC(Sl)502). 

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. 

Rohrer DC, Sundaralingam M (1970) Stereochemistry of nucleic acids and their constituents. XII. Crystal and molecular structure of a-D-amino-2 -deoxyadenosine monohydrate. J Am Chem Soc 92 4956 962... 

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