3-Ketosphinganine synthase

Write a reasonable mechanism for the 3-ketosphinganine synthase reaction, remembering that it is a pyridoxal phosphate-dependent reaction. 

Recall that sphingolipids in animals possess ceramide, a derivative of the amino alcohol sphingosine. The synthesis of ceramide begins with the condensation of pafrni-toyl-CoA with serine to form 3-ketosphinganine. This reaction is catalyzed by 3-ketosphinganine synthase, a pyridoxal-5 - phosphate-dependent enzyme. (Because... 

FIGURE 3.10 Biosynthetic pathway of ceramide. SPT, serine palmitoyltransferase 3-KSR, 3-ketosphinganine reductase Cer-Synthase, ceramide synthase. In fact, the reaction catalyzed by ceramide synthase leads to dihydroceramide. Ceramide is obtained by the secondary action of a desaturase that creates a trans double bond between carbons C4 and C5 of the sphingosine moiety (A). 

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