| | 1 | Author
| Siegrid Schoch, Wolfram Schäfer | Requires cookie* | | | Title
| Tetrahydrogeranylgeraniol, a Precursor of Phytol in the Biosynthesis of Chlorophyll a — Localization of the Double Bonds  | | | | Abstract
| Pheophytins esterified with phytol and tetrahydrogeranylgeraniol are isolated from etiolated oat seedlings after short (1 min) exposure to light and a subsequent dark period of 15 to 20 min. After saponification of the pheophytins, a mixture of the alcohols was isolated. The structure of tetra hydrogeranylgeraniol was established as 3,7,11,15-tetramethyl-zl2'14 hexadecadiene-l-ol (3a). The implications for chlorophyll biosynthesis are discussed. | | | |
Reference
| Z. Naturforsch. 33c, 408—412 (1978); received March 23 1978 | | | |
Published
| 1978 | | | |
Keywords
| Birthday Avena sativa, Gramineae, Oats, Chlorophyll Biosynthesis, Phytol | | | |
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| default:Reihe_C/33/ZNC-1978-33c-0408.pdf | | | | Identifier
| ZNC-1978-33c-0408 | | | | Volume
| 33 | |
| 2 | Author
| Kira Oikawa, Kenkichi Ebisui, Masayuki Sue, Atsushi Ishihara, Hajime Iwamura | Requires cookie* | | | Title
| Purification and Characterization of a ß-Glucosidase Specific for 2,4-Dihydroxy- 7-methoxy-l,4-benzoxazin-3-one (DIM BOA) Glucoside in Maize | | | | Abstract
| Occurrence and properties of hydroxamic acid glucoside glucosidase were investigated in 10-day-old, autotrophic maize (Zea mays L.) in which 2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one glucoside (DIMBOA-G) is a major benzoxazinone component. Crude ex tracts of both leaves and roots showed glucosidase activity for both DIMBOA-G and 2,4-dihydroxy-l,4-benzoxazin-3-one glucoside (DIBOA-G). A cation-exchange chromatography after cryoprecipitation of the extract from leaves gave a peak with both activities, and further purification by ion-exchange and hydroxyapatite chromatography gave a fraction with an apparent homogeneity, the purification being 560 fold. The K m values (m M) of the purified glucosidase were 0.16 for DIMBOA-G, 0.68 for DIBOA-G and 2.96 for p-nitrophenyl-ß-D-glucopyranoside. The activity on salicin and esculin was too low to be detected. The data indicate that a glucosidase specific for DIMBOA-G comes into contact with constitutive benzoxazinone glucosides producing defensive aglycone when plants are damaged by micro bial or insect attacks. tance of plants to deleterious microbes and insects. The benzoxazinones are also known to catalyti-cally degrade s-triazine herbicides and thus re sponsible for their detoxification (Willard and Penner, 1976). Recently, we have found in both wheat and maize that benzoxazinone glucosides occur in a high amount during the stage from germination to autotrophic growth, together with a lesser amount of free aglycones (Nakagawa et al., 1995; Ebisui et al., 1998). As the plants enter into the autotrophic growth stage, the glucosides decrease to a con stant, lower level, and the aglycones become bar ely detectable. In maize, we have found that a DIM BOA -G specific glucosidase also occurs con currently with the transient occurrence of benzo xazinones, suggesting that the specific glucosidase plays a role in microbial and insect attacks to pro duce defensive aglycones in a high amount during the vulnerable, juvenile stage of growth. In this study, we examined w hether the glucosidase that comes into contact with the glucosides when auto trophic tissue is disintegrated is a specific one. | | | |
Reference
| Z. Naturforsch. 54c, 181—185 (1999); received November 19 1998/January 11 1999 | | | |
Published
| 1999 | | | |
Keywords
| Benzoxazinones, Zea mays, Gramineae, ß-Glucosidase | | | |
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| default:Reihe_C/54/ZNC-1999-54c-0181.pdf | | | | Identifier
| ZNC-1999-54c-0181 | | | | Volume
| 54 | |
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