Feruloyl groups

SBP was incubated in the presence of carbohydrases either individually, or in pairs, and in the absence or presence of esterase, and the soluble incubation products assayed for feruloyl groups by HPLC. None of the carbohydrases used contained FAE activity. 

Gelation of sugar beet pectin is a coupling reaction of feruloyl groups with some oxidants in a way that releases free radicals (Thibault et al., 1991). 

Fig. 2 Hemicellulose (xylan backbone with arabinose, glucuronic acid and feruloyl groups) [32]... 

Figure 4.62 One-electron oxidation of feruloyl groups. The radicals can couple at all possible spin sites, although (3-04 is the most frequent, g Lignin, the matrix material of plant cells, is an oxidative polymer of three related alcohols, i-coumaryl, coniferyl and sinapyl alcohol, formed by coupling of radicals at all possible spin sites. The feruloyl side-chains of pectin and hemicellulose can participate in this polymer formation, generating covalent links between polysaccharides and lignin.

CE Family 1 is very large and contains members which do not act on carbohydrate-derived substrates. The crystal structure of a CE 1 domain of XynlOB modular enzyme from Clostridium thermocellum has been solved. " The CE 1 domain is a feruloyl esterase which hydrolyses the feruloyl groups attached to some arabinofuranosyl 05 groups in native xylan. (The Xyn lOB protein as a whole consists of two CBM 22 domains, a dockerin domain, and a GH 20 xylanase domain, and forms part of a cellulosome - see Section 5.10.) The enzyme has the common a/p hydrolase fold. Studies of ferulic acid complexes of the inactive alanine mutant of the active site serine revealed the classic catalytic triad, and two main-chain peptide NH bonds are in place to form an oxyanion hole . A remarkable feature is that the enzyme as repeatedly isolated was esterilied on the active site serine by phosphate or sulfate. 

In a study of the structure and functions of feruloylated pectins in primary cell walls in spinach, about one feruloyl group was found per sixty sugar residues ( ). Ferulic acid was determined after alkaline hydrolysis by the Folin-Ciocalteu phenol reagent. 

ND=not determined ND =Aw value not determined, but substrate is catalyzed - =no activity MFA=methyl ferulate Ara5F=feruloyl group on the C5 of arabinose Ara2F= feniloyl group on the C2 of arabinose ... 

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