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R. Krishnaveni

Bio: R. Krishnaveni is an academic researcher from Saveetha University. The author has contributed to research in topics: Monoclinic crystal system & Materials science. The author has an hindex of 3, co-authored 13 publications receiving 72 citations. Previous affiliations of R. Krishnaveni include Gulbarga University & University of Madras.

Papers
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TL;DR: The present study deals with the transformation of L-tyrosine to L-dopa by Acremonium rutilum, a fungal tyrosinase producer, isolated from decomposed banana stud, which appears to be the first report on A. r utilum as a polyphenoloxidase producer with both cresolase and catecholase activity.
Abstract: The present study deals with the transformation of L-tyrosine to L-dopa by Acremonium rutilum, a fungal tyrosinase producer, isolated from decomposed banana stud. This appears to be the first report on A. rutilum as a polyphenoloxidase producer with both cresolase and catecholase activity. Enriched Czapek-Dox agar was used for plate assay screening. Enriched potato dextrose broth was used for optimization studies, which induced high levels of L-dopa under submerged fermentation. A. rutilum gave the maximum L-dopa production (0.89 mg/ml) and tyrosinase activity (1095 U/mg) under the optimized parameters, that is, a temperature of 25°C, pH 5.5, an inoculum size of 2.5 ml, and an incubation time of 72–120 h, with L-tyrosine (5 mg/ml) as substrate. Five resolved bands, with Rf values of 0.73, 0.60, 0.54, 0.37, and 0.26, were observed, which confirmed the presence of L-dopa. This study involves the elevated profile of L-dopa production. Such study is needed, as L-dopa has the ability to control Parkinson’s disease.

52 citations

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TL;DR: In this article, the LVP macro crystals are grown by slow evaporations solution growth method and the empirical formula is C11H14N4O9, with a empirical formula of 9.9715

13 citations

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TL;DR: In this article, β-cyclodextrin is chemically modified to selectively introduce an acridinedione moiety on the primary face of the compound, which facilitates the introduction of an ethylene diamine modification which is finally condensed to a tetraketone.
Abstract: β -Cyclodextrin is chemically modified to selectively introduce an acridinedione moiety on the primary face. The synthesis involves the substitution of one of the primary hydroxyl groups of β -cyclodextrin by a tosyl group which facilitates the introduction of an ethylene diamine modification which is finally condensed to a tetraketone. The acridinedione modified β -cyclodextrin thus obtained was fully characterized by IR, NMR and Mass spectrometry. The photophysical properties of the compound were also analyzed. The potential of the modified β -cyclodextrin to act as an energy donor in FRET was investigated with a suitable acceptor.

7 citations


Cited by
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TL;DR: The synthesis of (S)-reticuline from dopamine by crude enzymes from transgenic Escherichia coli indicates that microbial systems that incorporate plant genes cannot only enable the mass production of scarce benzylisoquinoline alkaloid alkaloids but may also open up pathways for the production of novel benzylcolysis of tyrosine.
Abstract: Benzylisoquinoline alkaloids, such as the analgesic compounds morphine and codeine, and the antibacterial agents berberine, palmatine, and magnoflorine, are synthesized from tyrosine in the Papaveraceae, Berberidaceae, Ranunculaceae, Magnoliaceae, and many other plant families. It is difficult to produce alkaloids on a large scale under the strict control of secondary metabolism in plants, and they are too complex for cost-effective chemical synthesis. By using a system that combines microbial and plant enzymes to produce desired benzylisoquinoline alkaloids, we synthesized (S)-reticuline, the key intermediate in benzylisoquinoline alkaloid biosynthesis, from dopamine by crude enzymes from transgenic Escherichia coli. The final yield of (S)-reticuline was 55 mg/liter within 1 h. Furthermore, we synthesized an aporphine alkaloid, magnoflorine, or a protoberberine alkaloid, scoulerine, from dopamine via reticuline by using different combination cultures of transgenic E. coli and Saccharomyces cerevisiae cells. The final yields of magnoflorine and scoulerine were 7.2 and 8.3 mg/liter culture medium. These results indicate that microbial systems that incorporate plant genes cannot only enable the mass production of scarce benzylisoquinoline alkaloids but may also open up pathways for the production of novel benzylisoquinoline alkaloids.

295 citations

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TL;DR: This review compiles the recent data on biochemical and molecular properties of microbial tyrosinases, underlining their importance in the industrial use of these enzymes.
Abstract: Tyrosinase is a natural enzyme and is often purified to only a low degree and it is involved in a variety of functions which mainly catalyse the o-hydroxylation of monophenols into their corresponding o-diphenols and the oxidation of o-diphenols to o-quinones using molecular oxygen, which then polymerizes to form brown or black pigments. The synthesis of o-diphenols is a potentially valuable catalytic ability and thus tyrosinase has attracted a lot of attention with respect to industrial applications. In environmental technology it is used for the detoxification of phenol-containing wastewaters and contaminated soils, as biosensors for phenol monitoring, and for the production of L-DOPA in pharmaceutical industries, and is also used in cosmetic and food industries as important catalytic enzyme. Melanin pigment synthesized by tyrosinase has found applications for protection against radiation cation exchangers, drug carriers, antioxidants, antiviral agents, or immunogen. The recombinant V. spinosum tryosinase protein can be used to produce tailor-made melanin and other polyphenolic materials using various phenols and catechols as starting materials. This review compiles the recent data on biochemical and molecular properties of microbial tyrosinases, underlining their importance in the industrial use of these enzymes. After that, their most promising applications in pharmaceutical, food processing, and environmental fields are presented.

126 citations

Journal ArticleDOI
TL;DR: The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus and the nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence.

97 citations

Journal ArticleDOI
TL;DR: Copper oxide nanoparticles (CuONPs) were synthesized by radiolytic reactions of gamma radiation in the presence of melanin as a capping agent and exhibited excellent antimicrobial activity against food born Gram-positive, Gram-negative, and fungi; they can find potential applications for the food packaging approach.
Abstract: Melanin pigment is witnessed to be widely used in medicine, food, cosmetic preparations with strong hydrophobicity. Streptomyces cyaneus is utilized for the synthesis of melanin by optimizing culture conditions through screening of critical factors, by Response Surface Methodology as Plackett–Burman design (P-BD), while further statistical optimization was applied using Central Composite Design (CCD) for maximizing yield. Moreover, the impacts of gamma radiation and alternative frugal l-tyrosine, natural sources were studied as it predicted for remarkable rising in the pigment concentration. Herein unprecedented achievement was realized for melanin pigment production, (9.898 mg/ml) was obtaining by optimized culture condition. Also, 2.0% fava bean’s seed peel maximized melanin (9.953 mg/ml) and hence super-yield (11.113 mg/ml) was produced by a stimulus from gamma irradiation (2.5 kGy). The extracted melanin was confirmed chemically, UV–Vis, and FT-IR analysis. Copper oxide nanoparticles (CuONPs) were synthesized by radiolytic reactions of gamma radiation (30.0 kGy) in the presence of melanin as a capping agent. CuONPs were characterized by UV–Vis, DLS, XRD, and FT-IR. TEM analysis revealed the morphology of monodispersed CuONPs with a mean diameter 29.82 nm. CuONPs exhibited excellent antimicrobial activity against food born Gram-positive, Gram-negative bacteria, and fungi; they can find potential applications for the food packaging approach.

79 citations

Journal ArticleDOI
TL;DR: The future potential of biotechnological l-DOPA production as an industrial process is suggested and the electroenzymatic conversion system was recently introduced as a newly emerging scheme.
Abstract: L-DOPA (3,4-dihydroxyphenyl-L-alanine) has been widely used as a drug for Parkinson's disease caused by deficiency of the neurotransmitter dopamine. Since Monsanto developed the commercial process for L-DOPA synthesis for the first time, most of currently supplied L-DOPA has been produced by the asymmetric method, especially asymmetric hydrogenation. However, the asymmetric synthesis shows critical limitations such as a poor conversion rate and a low enantioselectivity. Accordingly, alternative biotechnological approaches have been researched for overcoming the shortcomings: microbial fermentation using microorganisms with tyrosinase, tyrosine phenol-lyase, or p-hydroxyphenylacetate 3-hydroxylase activity and enzymatic conversion by immobilized tyrosinase. Actually, Ajinomoto Co. Ltd commercialized Erwinia herbicola fermentation to produce L-DOPA from catechol. In addition, the electroenzymatic conversion system was recently introduced as a newly emerging scheme. In this review, we aim to not only overview the biotechnological L-DOPA production methods, but also to briefly compare and analyze their advantages and drawbacks. Furthermore, we suggest the future potential of biotechnological L-DOPA production as an industrial process.

77 citations