Use of isotopically labeled substrates reveals kinetic differences between human and bacterial serine palmitoyltransferase.

摘要: Isotope labels are frequently used tools to track metabolites through complex biochemical pathways and discern the mechanisms of enzyme-catalyzed reactions. Isotopically labeled l-serine is often monitor activity first enzyme in sphingolipid biosynthesis, serine palmitoyltransferase (SPT), as well labeling downstream cellular metabolites. Intrigued by effect that isotope may be having on SPT catalysis, we characterized impact different isotopologues catalytic recombinant isozymes from humans bacterium Sphingomonas paucimobilis. Our data show S. paucimobilis displays a clear with [2,3,3-D]l-serine, whereas human isoform does not. This suggests although both catalyze same chemical reaction, there underlying subtle differences their mechanisms. results suggest it activating small subunits play key role these mechanistic variations. study also highlights important consider type location substrate when they vitro vivo studies.