The growing relevance of biological ene reactions.

The ene reaction involves the addition of an 'ene' to an 'enophile.' The retro-ene reaction is the reverse of the ene reaction. In recent years various biological molecules have been found to form covalent intermediates (ene-adducts) that might be the result of an ene reactions.

N-Benzylnicotinamide and N-benzyl-1,4-dihydronicotinamide: useful models for NAD and NADH.

3-Aminocarbonyl-1-benzylpyridinium bromide (N-benzylnicotinamide, BNA), CHNO·Br, (I), and 1-benzyl-1,4-dihydropyridine-3-carboxamide (N-benzyl-1,4-dihydronicotinamide, rBNA), CHNO, (II), are valuable model compounds used to study the enzymatic cofactors NAD(P) and NAD(P)H. BNA was crystallized successfully and its structure determined for the first time, while a low-temperature high-resolution structure of rBNA was obtained. Together, these structures provide the most detailed view of the reactive portions of NAD(P) and NAD(P)H.