Ceramide aminoethylphosphonate

Figure 3 The structures of sphingomyelin (1), ceramide aminoethylphosphonate (2), and inositol phosphorylceramide (InsPCer) (3).

The structure of a ceramide aminoethylphosphonate from Metridium senile has been shown to be (21). Hydrolysis of (21) by phospholipase gave (20) which was identified by g.l.c. and mass spectrometry. The ceramide fraction after this hydrolysis was itself hydrolysed by alkali, and the fatty acids together with the long-chain bases were also identified by g.l.c.-m.s. The composition of the long-chain bases was found to differ between anemones captured in April and in August the former lacked sphingosine. 

An exact definition of primary and secondary metabolites is not very useful since it is deemed to be artificial. Although primary metabolism is to some extent similar in all organisms there are variations, major (photosynthetic/non-photosynthetic - aerobic/anaerobic organisms) as well as minor (bromotyrosine in sponge skeletons, ceramide aminoethylphosphonate in sea anemones (10)). This means that a secondary metabolite for one organism may assume the role as a primary one for another. From a purely formal point of view the distinction is meaningless and best abandoned. For classification purposes it still serves to delineate a large body of biochemicals in a convenient compilation. 

Figure 1. Ceramide aminoethylphosphonate (CAEP). When obtained from P. infestans the most common fatty acid is arachidonic acid and the most common long chain base is sphingosine.

It is a relatively simple matter to hydrolyse sphingomyelin and ceramide aminoethylphosphonate to ceramides with the enzyme phospholipase C from Clostridium welchii, and practical details of the... 

It is perhaps rather surprising, but intact ceramide aminoethylphosphonate from shell fish has been successfully subjected to GC separation in the form of the TMS ether derivative [601]. Presumably the phosphonate bond is much more stable than a phosphate at elevated temperatures. 

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