Diaminopimelate synthesis

The Grubbs method14 1 is readily applicable to the synthesis of other stereoisomers and can be expanded to include homologues with additional methylene units spanning the glycyl substructures. This method can also be applied to the stereoselective synthesis of selectively protected meso- or L,L-2,6-diaminopimelic acid and related differentially protected derivatives. [461... 

Alkaloid metabolism in lupine was proved by Wink and Hartmann to be associated with chloroplasts (34). A series of enzymes involved in the biosynthesis of lupine alkaloids were localized in chloroplasts isolated from leaves of Lupinus polyphylls and seedlings of L. albus by differential centrifugation. They proposed a pathway for the biosynthesis of lupanine via conversion of exogenous 17-oxosparteine to lupanine with intact chloroplasts. The biosynthetic pathway of lupinine was also studied by Wink and Hartmann (35). Two enzymes involved in the biosynthesis of alkaloids, namely, lysine decarboxylase and 17-oxosparteine synthetase, were found in the chloroplast stoma. The activities of the two enzymes were as low as one-thousandth that of diaminopimelate decarboxylase, an enzyme involved in the biosynthetic pathway from lysine to diaminopimelate. It was suggested that these differences are not caused by substrate availability (e,g., lysine concentration) as a critical factor in the synthesis of alkaloids. Feedback inhibition would play a major role in the regulation of amino acid biosynthesis but not in the control of alkaloid formation. 

Conjugate addition of radicals generated by decarboxylative fragmentation of (diacyloxyiodo)benzene 564 to dehydroamino acid derivatives 563 has been used in the synthesis of diaminopimelic acid analogues 565 (Scheme 3.223) [612]. 

Enzymes which could catalyze the next four reactions in the pathway have not been isolated from plants. Assuming that these reactions are analogous to those which occur in microorganisms, the NAD(P)H-dependent reduction of 2,3-dihydropicolinate to A -piperidine-2,6-dicarboxylate would be followed by acylation of the amino group (the latter reaction may involve prior nonen-zymatic hydrolysis of the C-N double bond). Acylation serves to protect the 2-amino group during the synthesis of the diamino intermediate either acetyl-CoA or succinyl-CoA is utilized in microorganisms. Deacylation of A -acyl-2,6-diaminopimelate results in the formation of a symmetrical l,l... 

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