Sinapate esters synthesis

Mutants Affecting the Final Stages of Sinapate Ester Synthesis. 52... 

MUTANTS AFFECTING THE FINAL STAGES OF SINAPATE ESTER SYNTHESIS... 

Figure 3.3 Synthesis of sinapate esters in Arahidopsis. SGT, sinapic acid UDPG sinapoyltransferase SMT, sinapoylglucose sinapoylmalate sinapate transferase SCT, sinapoylglucose sinapoylcholine sinapate transferase.

The 4-coumarate CoA ligase (4CL EC 6.2.1.12) enzyme activates 4-coumaric acid, caffeic acid, ferrulic acid, and (in some cases) sinapic acid by the formation of CoA esters that serve as branch-point metabolites between the phenylpropanoid pathway and the synthesis of secondary metabolites [46, 47]. The reaction has an absolute requirement for Mg " and ATP as cofactors. Multiple isozymes are present in all plants where it has been studied, some of which have variable substrate specificities consistent with a potential role in controlling accumulation of secondary metabolite end-products. Examination of a navel orange EST database (CitEST) for flavonoid biosynthetic genes resulted in the identification of 10 tentative consensus sequences that potentially represent a multi-enzyme family [29]. Eurther biochemical characterization will be necessary to establish whether these genes have 4CL activity and, if so, whether preferential substrate usage is observed. 

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