|Name||Mr. Hyunjun Choe|
|Organization or Institution||University of Florida|
|Topic||Biochemistry / Chem Bio.|
Effect of the active site arginine mutation on acyl-CoA substrate preference of serine palmitoyltransferase
Hyunjun Choe, Minsun Cha, and Jon D. Stewart*
Dept. of Chemistry, University of Florida
Sphingolipid analogues, derivatives of α-amino-β-hydroxyketones, have been shown critical biological activities. Despite the importance of the chemicals, conventional methods to synthesize the ketones require multiple reactions and purification steps. Thus, the ease of the synthesis of enantiomerically pure α-amino-β-hydroxyketones can benefit pharmaceutical research. The synthesis of these ketones via a one-step biocatalytic process could replace the conventional methods. Serine palmitoyltransferase (SPT) produces 3-keto-dihydrosphingosines from L-serine and long-chain acyl-CoAs. The irreversibility makes SPT an excellent candidate for the direct synthesis of (S)-α-amino-β-hydroxyketones. However, SPT shows a preference for long-chain acyl-CoAs. To expand the acyl-CoA substrate scope of the enzyme, we performed site-saturation mutagenesis on an active site arginine which is thought to act as a gate on the substrate channel. SPT R378K mutant showed higher activity and a greater preference toward acyl-CoAs with short alkyl chains, when compared to wild-type SpSPT.