Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of vitamin D-3 hydroxylated metabolites in Solanum malacoxylon was investigated. When crude leaf homogenates and subcellular fractions were incubated with [3H]vitamin D-3 and [3H]25-hydroxy-vitamin D-3 under conditions described for animal vitamin D-3-25-hydroxylase and 25-hydroxy-vitamin D-3-1 alpha-hydroxylase, respectively, labelled metabolites identified on the basis of their chromatographic properties as 25-hydroxy-vitamin D-3 and 1,25-dihydroxy-vitamin D-3 were formed. Other unidentified product metabolites were also detected. Vitamin D-3-25-hydroxylase activity was localized in microsomes and 25-hydroxy-vitamin D-3-1 alpha-hydroxylase in mitochondria and microsomes. Chromatography of sterols isolated from leaf extracts preincubated with beta-glucosidase on Sephadex LH-20 columns permitted the isolation of three biologically active fractions with elution properties similar to vitamin D-3, 25-hydroxy-vitamin D-3 and 1,25-dihydroxy-vitamin D-3, respectively. Ultraviolet spectra characteristic of vitamin D-3 and its metabolites were obtained after purification of the fractions by TLC. Co-chromatography of individual fractions with authentic metabolites on TLC provided further evidence that the plant contains vitamin D-3, 25-hydroxy-vitamin D-3 and 1,25-dihydroxy-vitamin D-3 as glucoside derivatives. These results suggest that a similar pathway of vitamin D-3 hydroxylation as in animals may be operative in S. malacoxylon.
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PMID:Synthesis and composition of vitamin D-3 metabolites in Solanum malacoxylon. 629 9

In cultured Solanum glaucophyllum we have recently described the operation of a light-independent pathway of 1alpha,25-dihydroxy-vitamin D(3) (1alpha,25(OH)(2)D(3)) biosynthesis which involves similar intermediates as in vertebrates. In this work we investigated factors influencing the formation of 1alpha,25(OH)(2)D(3) and related sterols in S. glaucophyllum grown in vitro in darkness. Callus tissue and cells cultured in Murashige and Skoog medium in the absence of light were employed. Lipids were extracted with chloroform-methanol. The remaining water soluble fraction was incubated with beta-glucosidase to release vitamin D(3) compounds from their glycoconjugated derivatives followed by organic solvent extraction. Vitamin D(3) derivatives were isolated by Sephadex LH-20 and high-performance liquid chromatography (HPLC). HPLC or competitive protein binding assays with intestine 1alpha,25(OH)(2)D(3) receptor and serum vitamin D binding protein were used to quantify the metabolites. The levels of 1alpha,25(OH)(2)D(3) in calli varied according to the tissue explant origin, e.g. stem>leaf>fruit. For all organs, the metabolite was mainly present as free sterol (>80% of total). There were larger amounts of 25(OH)D(3) than 1alpha,25(OH)(2)D(3). It was found that Ca(2+), auxin and kinetin are important factors upregulating 1alpha,25(OH)(2)D(3) synthesis in S. glaucophyllum tissue and cells. Irradiation with UV light increased vitamin D(3) but not 1alpha,25(OH)(2)D(3) levels. In agreement with these results, incubation of cells with [3H]25(OH)D(3) revealed a low conversion rate to [3H]1alpha,25(OH)(2)D(3). The operation of a light-dependent pathway formation of vitamin D(3) coupled to higher expression of 25(OH)D(3)-1alpha-hydroxylase may account for the large concentrations of 1alpha,25(OH)(2)D(3) normally found in differentiated field-grown plants.
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PMID:Effect of culture conditions on the synthesis of vitamin D(3) metabolites in Solanum glaucophyllum grown in vitro. 1152 17