scholarly journals Pigment Formation by Acetobacter acetigenum in a Lactate-buffered Glycerol Medium

Nature ◽  
1964 ◽  
Vol 204 (4956) ◽  
pp. 402-402 ◽  
Author(s):  
K. RAMAMURTI ◽  
C. P. JACKSON
Keyword(s):  
Pigment Formation ◽  
Glycerol Medium

scholarly journals One-Pot Three Component Synthesis of 2-(1H-Benzo[d]thiazole-2-yl)- N-Arylbenzamides in Glycerol Medium

2020 ◽  
Vol 32 (6) ◽  
pp. 1343-1351
Author(s):  
Swathi Thumula ◽  
Venkatesan Srinivasadesikan ◽  
Ravi K. Kottalanka ◽  
S. Rex Jeya Rajkumar ◽  
Balajee Ramchandran
Keyword(s):  
Docking Study ◽  
Molecular Docking Study ◽  
One Pot ◽  
Docking Result ◽  
Three Component Reaction ◽  
Antibacterial Target ◽  
Short Time ◽  
A549 Lung ◽  
Glycerol Medium ◽  
Mcf 7

In this work, a series of 2-(1H-benzo[d]thiazole-2-yl)-N-arylbenzamides is synthesized by using diethyl phthalate, anilines and 2-amino-benzenethiol by one-pot three component synthesis in glycerol medium. Phosphoric acid is used as an effective reagent for this one-pot three component reaction. This reaction got completed in a short time, easy workup and gave an excellent yield in glycerol medium. The N-arylbenzamides was found to have significant cytotoxic potentials against various cancer cells viz., A549 (lung cancer), HeLa (cervical cancer) and MCF-7 (breast cancer) using MTT assay. The molecular docking study is also employed to understand the binding mechanism of N-arylbenzamides against the antibacterial target. The docking result shows the binding energy of compound 4a is -8.6 kcal/mol. The binding affinity is a major concern and it shows that Asn and Thr residues have an interaction with compound 4a.

scholarly journals Melanogenesis Connection with Innate Immunity and Toll-Like Receptors

2020 ◽  
Vol 21 (24) ◽  
pp. 9769
Author(s):  
Saaya Koike ◽  
Kenshi Yamasaki
Keyword(s):  
Skin Pigmentation ◽  
Innate Immune ◽  
Mitogen Activated Protein Kinase ◽  
Ultraviolet Rays ◽  
Toll Like Receptors ◽  
Pigment Formation ◽  
Living Body ◽  
Pigmentary Disorders ◽  
Wide Range ◽  
Griscelli Syndrome

The epidermis is located in the outermost layer of the living body and is the place where external stimuli such as ultraviolet rays and microorganisms first come into contact. Melanocytes and melanin play a wide range of roles such as adsorption of metals, thermoregulation, and protection from foreign enemies by camouflage. Pigmentary disorders are observed in diseases associated with immunodeficiency such as Griscelli syndrome, indicating molecular sharing between immune systems and the machineries of pigment formation. Melanocytes express functional toll-like receptors (TLRs), and innate immune stimulation via TLRs affects melanin synthesis and melanosome transport to modulate skin pigmentation. TLR2 enhances melanogenetic gene expression to augment melanogenesis. In contrast, TLR3 increases melanosome transport to transfer to keratinocytes through Rab27A, the responsible molecule of Griscelli syndrome. TLR4 and TLR9 enhance tyrosinase expression and melanogenesis through p38 MAPK (mitogen-activated protein kinase) and NFκB signaling pathway, respectively. TLR7 suppresses microphthalmia-associated transcription factor (MITF), and MITF reduction leads to melanocyte apoptosis. Accumulating knowledge of the TLRs function of melanocytes has enlightened the link between melanogenesis and innate immune system.

scholarly journals The rosy locus in Drosophila melanogaster: xanthine dehydrogenase and eye pigments.

Genetics ◽  
1991 ◽  
Vol 129 (4) ◽  
pp. 1099-1109 ◽  
Author(s):  
A G Reaume ◽  
D A Knecht ◽  
A Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Structural Integrity ◽  
Present Report ◽  
Specific Interaction ◽  
Pigment Granule ◽  
Ultrastructural Localization ◽  
Xanthine Dehydrogenase ◽  
Pigment Formation ◽  
Antibody Staining ◽  
Pigment Granules

Abstract The rosy gene in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase (XDH). Mutants that have no enzyme activity are characterized by a brownish eye color phenotype reflecting a deficiency in the red eye pigment. Xanthine dehydrogenase is not synthesized in the eye, but rather is transported there. The present report describes the ultrastructural localization of XDH in the Drosophila eye. Three lines of evidence are presented demonstrating that XDH is sequestered within specific vacuoles, the type II pigment granules. Histochemical and antibody staining of frozen sections, as well as thin layer chromatography studies of several adult genotypes serve to examine some of the factors and genic interactions that may be involved in transport of XDH, and in eye pigment formation. While a specific function for XDH in the synthesis of the red, pteridine eye pigments remains unknown, these studies present evidence that: (1) the incorporation of XDH into the pigment granules requires specific interaction between a normal XDH molecule and one or more transport proteins; (2) the structural integrity of the pigment granule itself is dependent upon the presence of a normal balance of eye pigments, a notion advanced earlier.

scholarly journals Bile-pigment formation from different leghaemoglobins. Methine-bridge specificity of coupled oxidation

1978 ◽  
Vol 176 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Päivi Lehtovaara ◽  
Ulla Perttilä
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Broad Bean ◽  
Amino Acid Sequences ◽  
Second Step ◽  
Bile Pigment ◽  
Site Specificity ◽  
Amino Acid Residues ◽  
Reaction Step ◽  
Pigment Formation

The coupled oxidation of leghaemoglobins with O2 and ascorbate yielded oxyleghaemoglobin in the first reaction step, and the second step was the degradation of haem characterized by an A675 increase. Leghaemoglobins were degraded to biliverdin isomers specifically, depending on the structure of the protein. The main leghaemoglobin components of Glycine (soya bean) and Phaseolus (kidney bean) were degraded to biliverdin mixtures containing about 50% of the β-form, about 30% of the α-form and about 20% of the δ-isomer, whereas the leghaemoglobin I components of Vicia (broad bean) and Pisum (pea) were degraded almost exclusively to the β-isomer, with traces of the α-isomer. The amino acid sequences of Glycine and Phaseolus leghaemoglobins resemble each other, as do those of Vicia and Pisum. The site specificity of bile-pigment formation from leghaemoglobins can be tentatively explained by specific differences in the amino acid sequences at those regions of the polypeptide chain that are in the vicinity of the appropriate methine bridges. The ligand-binding site in different leghaemoglobins may be outlined on the basis of the present results, supposing that the haem is degraded when a reduction product of haem-bound O2 reacts with a methine bridge of the haem, and that the bridge specificity is regulated by hindering amino acid residues that determine the location of the bound O2. The residue phenylalanine-CD1 appears to be further away from the haem plane or in a markedly more flexible position in leghaemoglobins than in mammalian globins. The haem-bound oxygen atom B, in Fe–O(A)–O(B), seems to be free to rotate in all directions except that of the γ-bridge in Glycine and Phaseolus leghaemoglobins, but its position in Vicia and Pisum leghaemoglobin I might be restricted to the direction of the β-methine bridge.

Effect of Liquid Flow on Pigment Formation of Red Beet Hairy Roots.

1999 ◽  
Vol 32 (3) ◽  
pp. 370-373 ◽  
Author(s):  
Yoshio Hitaka ◽  
Masahiro Kino-oka ◽  
Masahito Taya ◽  
Setsuji Tone
Keyword(s):  
Hairy Roots ◽  
Liquid Flow ◽  
Pigment Formation ◽  
Red Beet

Brown pigmentation of Xanthomonas campestris pv. phaseoli associated with homogentisic acid

1994 ◽  
Vol 40 (1) ◽  
pp. 28-34 ◽  
Author(s):  
P. H. Goodwin ◽  
C. R. Sopher
Keyword(s):  
Xanthomonas Campestris ◽  
Culture Media ◽  
Taxonomic Status ◽  
Homogentisic Acid ◽  
Brown Pigment ◽  
Pigment Formation ◽  
Dihydroxyphenylacetic Acid ◽  
Alkaline Conditions ◽  
The Media ◽  
Number Of Bacteria

The diffusible brown pigment produced by some strains of Xanthomonas campestris pv. phaseoli was found to be due to the secretion and subsequent oxidation of homogentisic acid (2, 5-dihydroxyphenylacetic acid) rather than tyrosinase activity as previously reported. Homogentisic acid is an intermediate in tyrosine catabolism for a number of bacteria. Brown-pigmented strains appeared to be disrupted in tyrosine catabolism and could not use tyrosine as a nutrient. Nonpigmented strains, however, could utilize tyrosine as a nutrient, and although they secreted homogentisic acid, the levels were approximately 1/100th that of brown-pigmented strains. Production of brown pigment was stimulated by tyrosine and repressed by glucose. Growth in glucose resulted in a drop in the pH of the media, and the greatest pigment formation was associated with a shift to alkaline conditions in the culture media. By buffering the media near pH 7.0, brown pigment formation was repressed, even though unoxidized homogentisic acid accumulated in the culture media. The disruption of tyrosine catabolism corresponds to other reports describing differences between brown-pigmented and nonpigmented strains, and provides further support for the retention of a special taxonomic status for the brown-pigmented strains.Key words: homogentisic acid, pigments, Xanthomonas, fuscans.

scholarly journals Convergent evolution of a novel blood-red nectar pigment in vertebrate-pollinated flowers

2021 ◽  
Author(s):  
Rahul Roy ◽  
Nickolas Moreno ◽  
Stephen A Brockman ◽  
Adam Kostanecki ◽  
Amod Zambre ◽  
...  
Keyword(s):  
Convergent Evolution ◽  
Alcohol Oxidase ◽  
Enzymatic Activities ◽  
Red Pigment ◽  
Pollinator Visitation ◽  
Pigment Formation ◽  
Red Color ◽  
Genes Encoding ◽  
Pigment Precursor ◽  
Imine Bond

Nesocodon mauritianus (Campanulaceae) produces a blood-red nectar that has been proposed to serve as a visual attractant for pollinator visitation. Here we show that the red color of the nectar is derived from a novel alkaloid termed nesocodin. The first nectar produced is acidic and pale yellow in color, but slowly becomes alkaline before taking on its characteristic red color. Three enzymes secreted into the nectar are either necessary or sufficient for pigment production, including (1) a carbonic anhydrase that creates an alkaline environment, (2) an aryl alcohol oxidase that generates sinapaldehyde, a pigment precursor, and (3) a ferritin-like catalase that protects nesocodin from degradation by hydrogen peroxide. Our findings demonstrate how these three enzymatic activities allow for the condensation of sinapaldehyde and proline to form a novel pigment with a stable imine bond, which in turn is attractive to Phelsuma geckos, the presumed pollinators of Nesocodon. We also identify nesocodin in the red nectar of the distantly related Jaltomata herrerae and provide evidence for convergent evolution of this trait. While the overall enzymatic activities required for red pigment formation in both Nesocodon and J. herrerae nectars are identical, the associated genes encoding the enzymes are not orthologous and, in the case of the aryl alcohol oxidase, even belong to different protein families. This work cumulatively identifies a novel, convergently evolved trait in two vertebrate-pollinated species, suggesting the red pigment is selectively favored and that only a limited number of compounds are likely to underlie this adaptation.

scholarly journals L-DOPA dioxygenase of the fly agaric toadstool: revision of the dodA gene sequence and mechanism of enzymatic pigment production

2020 ◽  
Author(s):  
Douglas M. M. Soares ◽  
Letícia C. P. Gonçalves ◽  
Caroline O. Machado ◽  
Larissa Cerrato Esteves ◽  
Cassius V. Stevani ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Kinetic Modelling ◽  
Enzymatic Catalysis ◽  
Heme Iron ◽  
Start Codon ◽  
Amino Acid Residues ◽  
Coding Region ◽  
Biotechnological Production ◽  
Pigment Formation ◽  
Alternative Start Codon

ABSTRACTl-DOPA extradiol dioxygenases (DODAs) catalyze the production of betalains and hygroaurins pigments. The sequence of the DODAs found in Caryophyllales and Basidiomycetes are not conserved, although betalains are produced both by plants and fungi. Here we revise the coding region of the dodA gene of fly agaric [Amanita muscaria (L.) Lam.] and describe an alternative start codon downstream that enables the heterologous expression of AmDODA, a promiscuous l-DOPA dioxygenase. AmDODA is 43-amino acid residues shorter than the recombinant DODA previously reported but catalyzes the formation of two isomeric seco-DOPAs that are the biosynthetic precursors of betalains and hygroaurins. The putative active site of AmDODA contains two distinct His-His-Glu motifs that can explain the dual cleavage of l-DOPA according to the mechanism proposed for non-heme iron-dependent dioxygenases. Upon addition of excess l-DOPA, both the betaxanthin and hygroaurin adducts of l-DOPA are produced. The kinetic parameters of enzymatic catalysis at pH 8.5 are similar to those reported for other l-DOPA dioxygenases. The rate constants for the conversion of l-DOPA into the betalamic acid and muscaflavin were estimated by kinetic modelling allowing the proposal of a mechanism of pigment formation. These results contribute to understanding the biosynthesis of bacterial, fungal and plant pigments, for the biotechnological production of hygroaurins, and for the development of more promiscuous dioxygenases for environmental remediation.

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