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Carlo dela Se?a Kenneth M. Riedl Sureshbabu Narayanasamy Robert W. Curley Jr. Steven J. Schwartz Earl H. Harrison 《The Journal of biological chemistry》2014,289(19):13661-13666
β-Carotene 15–15′-oxygenase (BCO1) catalyzes the oxidative cleavage of dietary provitamin A carotenoids to retinal (vitamin A aldehyde). Aldehydes readily exchange their carbonyl oxygen with water, making oxygen labeling experiments challenging. BCO1 has been thought to be a monooxygenase, incorporating oxygen from O2 and H2O into its cleavage products. This was based on a study that used conditions that favored oxygen exchange with water. We incubated purified recombinant human BCO1 and β-carotene in either 16O2-H218O or 18O2-H216O medium for 15 min at 37 °C, and the relative amounts of 18O-retinal and 16O-retinal were measured by liquid chromatography-tandem mass spectrometry. At least 79% of the retinal produced by the reaction has the same oxygen isotope as the O2 gas used. Together with the data from 18O-retinal-H216O and 16O-retinal-H218O incubations to account for nonenzymatic oxygen exchange, our results show that BCO1 incorporates only oxygen from O2 into retinal. Thus, BCO1 is a dioxygenase. 相似文献
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Subramani Ramesh Mahalingam Rajesh Narayanasamy Mathivanan 《Bioprocess and biosystems engineering》2009,32(6):791-800
Totally 191 different marine actinomycetes were isolated from 256 different marine samples collected from the Bay of Bengal
and its associated Pulicat lake and Pichavaram mangrove, India. Among them, 157 produced caseinase, 113 produced gelatinase
and 108 produced both the protease enzymes. An isolate coded as MML1614 was selected for further study as it exhibited high
proteolytic activity. The MML1614 was identified as Streptomyces fungicidicus based on polyphasic taxonomical approach including 16S rRNA sequence analysis. The culture conditions were standardized for
the growth and protease production in S. fungicidicus MML1614. The protease was isolated from a 6-day-old culture filtrate of S. fungicidicus MML1614 and partially purified up to 4.5-fold. The protease was optimally active at pH 9 and 40 °C and it was stable up to
pH 11 and 60 °C. PMSF and NaCl inhibited the enzyme activity up to 22 and 11%, respectively. The partially purified protease
removed the blood stain more effectively when combined with different detergents than the detergents alone. 相似文献
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Control of blast and sheath blight diseases of rice using antifungal metabolites produced by Streptomyces sp. PM5 总被引:2,自引:2,他引:0
Vaiyapuri R. Prabavathy Narayanasamy Mathivanan Kandasamy Murugesan 《Biological Control》2006,39(3):313-319
Two antifungal aliphatic compounds, SPM5C-1 and SPM5C-2 with a lactone and ketone carbonyl unit, respectively obtained from Streptomyces sp. PM5 were evaluated under in vitro and in vivo conditions against major rice pathogens, Pyricularia oryzae and Rhizoctonia solani. These compounds were dissolved in distilled water/medium to get the required concentrations. The well diffusion bioassay indicated that the of SPM5C-1 remarkably inhibited the mycelial growth of P. oryzae and R. solani in comparison to SPM5C-2. Though SPM5C-2 showed low antifungal activity against P. oryzae, it was not active against R. solani. Further, SPM5C-1 completely inhibited the growth of P. oryzae and R. solani at concentrations of 25, 50, 75 and 100 μg/ml. Greenhouse experiments revealed that spraying of SPM5C-1 at 500 μg/ml on rice significantly decreased blast and sheath blight development by 76.1% and 82.3%, respectively, as compared to the control with a corresponding increase in rice grain yield. 相似文献
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Efrem Kentiba Soumitra Mondal D. Mathivanan Mala George 《Chronobiology international》2013,30(12):1742-1747
ABSTRACTThe purpose of this study was to compare chronotype preferences of college students from high- and low-altitude backgrounds living in a tropical setting of Ethiopia. Chronotype (morningness–eveningness) is a preference for a given time of day for physical or mental activities. The present cross-sectional study employed Horne and Osteberg Morningness-Eveningness Questionnaires to evaluate chronotype preferences. The chronotype preference of 264 male college students from varied altitude backgrounds indicated significant differences (p < 0.001). Our findings confirm our hypothesis, of the prevalence of M-types dominant chronotype among college students at low than high altitude. However, we did not confirm our second hypothesis, since students from high-altitude backgrounds were generally I-type dominant chronotype. Similarly, students’ academic performances from low- compared to high-altitudes backgrounds also indicated significant differences (p < 0.003). Better academic performances were seen in students with I-type chronotype orientations from high altitudes. 相似文献
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Mathivanan Packiarajan Michel Grenon Samuel Zorn Allen T. Hopper Andrew D. White Gamini Chandrasena Xiaosui Pu Robbin M. Brodbeck Albert J. Robichaud 《Bioorganic & medicinal chemistry letters》2013,23(14):4037-4043
A new series of potent fused thiazole mGlu5 receptor positive allosteric modulators (PAMs) (10, 11 and 27–31) are disclosed and details of the SAR and optimization are described. Optimization of alkynyl thiazole 9 (Lu AF11205) led to the identification of potent fused thiazole analogs 10b, 27a, 28j and 31d. In general, substituted cycloalkyl, aryl and heteroaryl carboxamides, and carbamate analogs are mGlu5 PAMs, whereas smaller alkyl carboxamide, sulfonamide and sulfamide analogs tend to be mGlu5 negative allosteric modulators (NAMs). 相似文献
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Benson Edagwa Yiran Wang Prabagaran Narayanasamy 《Bioorganic & medicinal chemistry letters》2013,23(22):6138-6140
A glyoxalase inhibitor was synthesized and tested against Staphylococcus aureus for first time and showed MIC90 of 20 μg/ml. Henceforth, we synthesized unnatural azide derivative of the same inhibitor to improve the biological activity. In that order, an azide carboxylate was synthesized from dimethyl tartrate by tosylation and azide substitution. The synthesized, azide compound was coupled with glutathione derivative in high yield and tested against S. aureus and showed improved MIC90 of 5 μg/ml. In general, it can be also easily converted to unnatural β-amino acid in good yield. The shown methodology will be extended to study induced suicide in Burkholderia mallei, Francisella tularensis and Mycobacterium tuberculosis in future. 相似文献
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Carlo dela Se?a Sureshbabu Narayanasamy Kenneth M. Riedl Robert W. Curley Jr. Steven J. Schwartz Earl H. Harrison 《The Journal of biological chemistry》2013,288(52):37094-37103
Humans cannot synthesize vitamin A and thus must obtain it from their diet. β-Carotene 15,15′-oxygenase (BCO1) catalyzes the oxidative cleavage of provitamin A carotenoids at the central 15–15′ double bond to yield retinal (vitamin A). In this work, we quantitatively describe the substrate specificity of purified recombinant human BCO1 in terms of catalytic efficiency values (kcat/Km). The full-length open reading frame of human BCO1 was cloned into the pET-28b expression vector with a C-terminal polyhistidine tag, and the protein was expressed in the Escherichia coli strain BL21-Gold(DE3). The enzyme was purified using cobalt ion affinity chromatography. The purified enzyme preparation catalyzed the oxidative cleavage of β-carotene with a Vmax = 197.2 nmol retinal/mg BCO1 × h, Km = 17.2 μm and catalytic efficiency kcat/Km = 6098 m−1 min−1. The enzyme also catalyzed the oxidative cleavage of α-carotene, β-cryptoxanthin, and β-apo-8′-carotenal to yield retinal. The catalytic efficiency values of these substrates are lower than that of β-carotene. Surprisingly, BCO1 catalyzed the oxidative cleavage of lycopene to yield acycloretinal with a catalytic efficiency similar to that of β-carotene. The shorter β-apocarotenals (β-apo-10′-carotenal, β-apo-12′-carotenal, β-apo-14′-carotenal) do not show Michaelis-Menten behavior under the conditions tested. We did not detect any activity with lutein, zeaxanthin, and 9-cis-β-carotene. Our results show that BCO1 favors full-length provitamin A carotenoids as substrates, with the notable exception of lycopene. Lycopene has previously been reported to be unreactive with BCO1, and our findings warrant a fresh look at acycloretinal and its alcohol and acid forms as metabolites of lycopene in future studies. 相似文献