Biosynthesis of gallotannins

✍ Scribed by Klaus Denzel; Georg G. Gross

• Book ID: 104659913
• Publisher: Springer-Verlag
• Year: 1991
• Tongue: English
• Weight: 534 KB
• Volume: 184
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00197959

✦ Synopsis

Cell-free extracts from leaves of Rhus typhina L. (sumach) were found to transfer the 1-O-galloyl moiety of 1,6-di-O-galloyl-fl-o-glucose to the 2-position of the same compound, yielding 1,2,6-tri-O-galloyl-fl-Dglucose and leaving 6-O-galloylglucose as the deacylated by-product. The enzyme catalyzing this 'disproportionation' was purified almost 1700-fold. It had a molecular weight of approx. 56 000, a Km value of 11.5 raM, was stable between pH 4.5 and 6.5, and most active at pH 5.9 and 40~

The systematic name "l,6-di-O-galloylglucose: 1,6-di-O-galloylglucose 2-O-galloyltransferase" (EC 2.3.1.) was proposed for this new enzyme whose detection provided evidence that, in addition to fl-glucogallin (1-O-galloyl-fl-o-glucose), higher substituted glucose esters also have the potential to serve as acyl donors in the biosynthesis of gallotannins.