Quinate 3-hydroxylase

Figure 4.1 Current view of the phenylpropanoid metabolism. PAL, phenylalanine ammonia-lyase C4H, cinnamate 4-hydroxylase 4CL, 4-coumarate CoA-ligase HCT, hydroxycinnamoyl-CoAishikimate/quinate hydroxycinnamoyltransferase 3-hydroxylase, 4-hydroxycinnamoylshikimate/quinate 3-hydroxylase.

The substitution of the phenyl ring necessary for the biosynthesis of coniferyl alcohol (3.79) and sinapyl alcohol (3.81) begins with the hydroxylation of C3. This is a conversion that requires the formation of the ester of /5-coumaroyl-CoA with D-quinate (3.73) or shikimate (3.74) catalyzed by the enzyme hydroxycinnamoyl-CoA shikimate/quinate hydroxy-cinnamoyl transferase (HCT Hoffmann et al., 2003). The hydroxylation of this ester intermediate is catalyzed by the enzyme /i-coumarovl-Co A 3 -hydroxylase (C3 H Schoch et al., 2001 Franke et al., 2002a,b). The resulting shikimate or quinate ester (3.75 3.76) is subsequently hydrolyzed by the same HCT, resulting in caffeoyl-CoA (3.36). 

Figure 3-9. Biosynthesis of monolignols. The enzymes involved in this pathway are ( ) hydroxycinnamoyl-CoA shikimate/quinate hydroxy-cinnamoyl transferase, (b) p-coumaroyl-CoA 3 -hydroxylase (E.C. 1.14.14.1), (c) caffeoyl-CoA O-methy 1 Iranslerasc (E.C. 2.1.1.104), (d) cinnamoyl-CoA reductase (E.C. 1.2.1.44) (e) cinnamyl alcohol dehydrogenase (E.C. 1.1.1.195), (f) coniferyl aldehyde/coniferyl alcohol 5-hydroxylase (E.C. 1.14.13), (g) coniferaldehyde/coniferyl alcohol O-methyltransferase (E.C. 2.1.1.68).

Kuhnl, T., Koch, U., Heller, W., and Wellmann, E., 1987, Chlorogenic acid biosynthesis characterization of a light induced microsomal 5-0-(4-coumaroyl)-D-quinate/shikimate 3 -hydroxylase from carrot (Daucus carota L.) cell suspension cultures, Arch. Biochem. Biophys. 258 226-232. 

HAL and PAL Proposed Tyr loop-in model for breathing motion tor substrate access The molecular basis of PAL and TAL substrate versatility Hydroxycinnamoyl CoA Shikimate/Quinate Hydroxycinnamoyltransferase Cytochrome P-450 Hydroxylation Reactions (Cinnamate 4-Hydroxylase, p-Coumarate 3-Hydroxylase , and Ferulate 5-Hydroxylase ) Comparison to Bacterial/Mammalian P-450s Subcellular localization of C4H, pC3H , and F5H ... 

Figure 4 Current view of the phenylpropanoid pathway to the monolignols 19-23. 4CL, 4-hydroxycinnamate coenzyme Aligases pC3H , p-coumarate 3-hydroxylase C4H, cinnamate 4-hydroxylase CAD, cinnamyl alcohol dehydrogenases CCOMT, hydroxycinnamoyl CoA O-methyltransferases CCR, cinnamoyl-CoA oxidoreductases COMT, caffeic acid O-methyltransferases F5H , ferulate 5-hydroxylase HCT, hydroxycinnamoyl-CoA shikimate hydroxycinnamoyltransferase HOT, hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase PAL, phenylalanine ammonia lyase TAL, tyrosine ammonia lyase.

Figure 3.1 Primary flux of carbon through phenylpropanoid pathway in Arabidopsis. PAL, phenylalanine ammonia-lyase 4CL, 4-(hydroxy)cinnamoyl CoA ligase C4H, cinnamate 4-hydroxylase HCT, hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase C3 H, /7-coumaroylshikimate 3 -hydroxylase CCoAOMT, caffeoyl CoA O-methyltransferase F5H, ferulate 5-hydroxylase COMT, caffeic acid/5-hydroxyferulic acid o-methyltransferase CCR, cinnamoyl CoA reductase CAD, cinnamyl alcohol dehydrogenase. Not depicted is the HCT catalyzed synthesis of/r-coumaroyl quinate.

D-Quinate/Shikimate 3 -Hydroxylase from Carrot (Daucus-Carota L) Cell-Suspension Cultures, rcA. Biochem. Biophys., 1987, 258, 226-232. 

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