Cardenolide glucohydrolases

Cardenolide glucohydrolase II Another CGH, termed CGH 11, was isolated from D. lanata and D. heywoodii leaves and cell cultures. This soluble enzyme hydrolyses cardenolide disaccharides with a terminal glucose and appears to be quite specific for glucoevatromonoside, which is supposed to be an intermediate in the formation of the cardenolide tetrasaccharides. The tetrasac-charides, deacetyllanatoside C and purpureaglycoside A, which are rapidly hydrolysed by CGH 1 (see Section 6.3.1.13) were very poor substrates for CGH II (Hornberger et al, 2000). 

A clone of cardenolide 16 -0-glucohydrolase cDNA (CGH I) was obtained from D. lanata. The amino acid sequence derived from CGH I showed high homology to a widely distributed family of (3-glucohydrolases (glycosyl hydrolases family 1). The recombinant CGH I protein produced in Escherichia coli had CGH 1 activity. CGH 1 mRNA was detected in leaves, flowers, stems and fruits of D. lanata (Framm et ah, 2000). 

Framm, J.J., Peterson, A., Thoeringer, C., Rangert, A., Homung, E., Feussner, 1., Luckner, M. and Lindemann, P. (2000) Cloning and functional expression in Escherichia coli of a cDNA encoding cardenolide 16-O-glucohydrolase from Digitalis lanata Ehrh. Plant Cell Physiol, 41,1293-8. 

Homberger, M., Boettigheimer, U., Hillier-Kaiser, A. and Kreis, W. (2000) Purification and characterisation of the cardenolide-specific p-glucohydrolase CGH It from Digitalis lanata leaves. Plant Phi/siol. Biochem., 38, 929-36. 

Kreis, W. and May, U. (1990) Cardenolide glucosyltransferases and glucohydrolases in leaves and cell cultures of three Digitalis (Scrophulariaceae) species.. Plant Physiol, 136, 247-52. 

Schoninger, R., Lindemann, P, Grimm, R., Eckerskom, C. and Luckner, M. (1998) Purification of the cardenolide 16-O-glucohydrolase from Digitalis lanata EHRH. 

Shi, H. and Lindemarm, P. (2006) Expression of recombinant Digitalis lanata EHRH. cardenolide 16-O-glucohydrolase in Cucumis sativus L. hairy roots. Plant Cell Rep., 25,1193-8. 

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