Catálogo de publicaciones - libros

Inositol is a deceptively simple molecule. On closer study, a number of sophisticated stereochemical, prochiral, chiral, and conformational issues associated with inositols and their derivatives become evident. Inositols, in particular myo -inositol, play a central role in cellular metabolism. An array of complicated molecules that incorporate the inositol moiety are found in nature. Structural heterogeneity of inositol derivatives is compounded by the presence of stereo- and regioisomers of the inositol unit. Because of the large number of isomeric inositols and their derivatives present in nature, a detailed understanding of the structural, stereochemical, and nomenclature issues involving inositol and its derivatives is essential to investigate biological aspects. A discussion of the stereochemical, conformational, prochiral, chiral, and nomenclature issues associated with inositols and the structural variety of insoitol derivatives is presented in this chapter.

The first and rate-limiting step in the biosynthesis of myo -inositol is the conversion of D -glucose 6-phosphate to 1 L - myo -inositol 1-phosphate catalyzed by 1 L - myo -inositol 1-phosphate synthase (MIP synthase). MIP synthase has been identified in a wide variety of organisms from bacteria to humans and is relatively well-conserved throughout evolution. It is probably homotetrameric in most if not all cases and always requires NAD^+ as a cofactor, with NADH being reconverted to NAD^+ in the catalytic cycle. This review focuses on the structure and mechanism of MIP synthase, with a particular emphasis on the mechanistic insights that have come from several recent structures of the enzyme. These include the structure of the enzyme from Saccharomyces cerevisiae, Archeoglobus fulgidus and Mycobacterium tuberculosis .