Part A. Sample and Standards Preparation In Chapter 18 , the extraction procedures for recovery of the phosphoinositols and phosphoinositides from cells are described, together with simple separation procedures to resolve them into their general classes (InsP 1 ; InsP 2 , and so on, and PtdIns, PtdInsP, and PtdInsP 2 ). However the metabolism of phosphoinositols is complex ( 1 , 2 ), leading to the formation of several isomeric forms in each class (seeFig.1 of Chapter 18 and Note Al ). Fig. 1. Basic chemistry of myo-inositol compounds. The three-dimensional structure (top left) and Haworth projection of myo-inositol (top right) are shown, together with the numbering of the carbon atoms by the D-numbenng system. Only C-C and C-OH bonds are shown, and the line of symmetry is indicated by a dotted line (for further details,seeref. 20). The reaction sequence for the conversion of the phosphoinositides (PtdIns) to phosphoinositols (InslP) via glycerophosphoinositol (GroPIns) and the glycolaldehyde intermediate is also shown (bottom)
