Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.99.3 (PRE)
 1,923 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of purified DNA photolyase from Baker's yeast is enhanced by a compound (Activator (III)) obtained from yeast by chloroform extraction ion exchange chromatography and gel filtration. Thin layer chromatography and spectral data indicate that the compound is homogeneous. Activator III emits at 350 and 440 nm when excited at 290 nm, and emits at 440 nm when excited at 358 nm. After acid hydrolysis, emission at 440 nm is produced only by excitation at 358 nm, indicating that activator (III) contains two separate chromophoric moieties. The chromophore excited by 358 nm light has a pK of 9-11, while the other chromophore has a pK of 4-5, and possibly of 9-11. The enhancement of photolytic activity by activator (III) at a concentration equimolar with that of the enzyme and the similarity of the fluorescent spectra of the activator with that of heat-denatured photolyase, suggests that the activator may be the chromophore associated with the enzyme.
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PMID:Purification from baker's yeast of an activator of DNA photolyase. 1 32

1. The binding of DNA photolyase, the enzyme which uncouples cyclobutadipyrimidines in DNA upon illumination, to its substrate was enhanced by a substance isolated from acidified autolysates of baker's yeast. 2. This substance, referred to as activator, was partially purified by chloroform extraction, ion-exchange chromatography on Dowex 50 and DEAE-cellulose, and gel filtration on Sephadex G-10. Upon lyophilization and storage at -20 degrees C, it was converted to a potent inhibitor of enzyme binding to substrate. 3. The inhibitor appeared as a single band in two thin-layer chromatography systems and was detected by ultraviolet absorbance, fluorescence, and ninhydrin staining. 4. The similarity between the fluorescence spectra of the inhibitor and the enzyme suggested that the inhibitor was structurally analogous to a chromophore in the enzyme and that the activator from which the inhibitor was derived may be the active chromophore of the enzyme.
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PMID:Purification of an inhibitor of DNA photolyase with fluorescent spectra similar to those of the enzyme. 109 Dec 98

beta-Sitosterol (SI-0), beta-sitosterol glucoside (SI-1), dioscin (SI-2), methyl protoprosapogenin A of dioscin (SI-3), methyl protodioscin (SI-4) and protodioscin (SI-5) were isolated and characterized from the whole plant of Solanum indicum L. (Solanaceae). Except for beta-sitosterol, these compounds have not been previously isolated from Solanum indicum L. Both CHCl3 soluble (SI-IV) and insoluble (SI-V) fractions of the ethanolic extract (SI-I) showed cytotoxicity on seven cancer cell lines: Colo-205 (colon), KB (nasopharynx), HeLa (uterine cervix), HA22T (hepatoma), Hep-2 (laryngeal epidermoid), GBM8401/TSGH (glioma) and H1477 (melanoma). The purified constituents, SI-2 and SI-4 showed more potent effects by DEA and MTT assay. SI-2,3,4 and 5 also demonstrated cytotoxicity on cultured C6 glioma cells by PRE assay, ans SI-3,4 and 5 showed a tumor inhibitory effect in vivo in C6 glioma cells. In addition, SI-2 had an inhibitory effect on the DNA synthesis of C6 glioma cells at 10 micrograms/ml.
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PMID:Experimental antitumor agents from Solanum indicum L. 176 63