[77] Tyrosinase (Neurospora crassa)

Horowitz, N. H.; Fling, Marguerite; Horn, George

doi:10.1016/0076-6879(71)17249-7

Cited by 62 publications

(34 citation statements)

References 7 publications

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“…PO activity in the humoral fluid and eluted fractions were assayed by the method of Horowitz and Shen [38] with slight modifications. An aliquot of 100 ml of the humoral fluid and eluted fractions was mixed with 360 ml of 10 mM sodium cacodylate (CAC) buffer (pH 7.0), 25 ml of 200 mM CaCl 2 and 15 ml of 1% SDS.…”

Section: Po Activity Assaymentioning

confidence: 99%

Purification and characterisation of phenoloxidase from amphioxus Branchiostoma belcheri tsingtauense

Pang

Zhang

Shi

et al. 2005

Fish & Shellfish Immunology

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Section: Po Activity Assaymentioning

confidence: 99%

Purification and characterisation of phenoloxidase from amphioxus Branchiostoma belcheri tsingtauense

Pang

Zhang

Shi

et al. 2005

Fish & Shellfish Immunology

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“…At the end of the induction phase the biomass was harvested by filtration, partially dried by pressing between filter paper and a representative sample taken for further analysis. Estimation of tyrosinase was carried out as described by Horowitz and co-workers, 6 and sugar was assayed by the standard DNS method.' All experiments were carried out at temperature of 28 * 2°C.…”

Section: Methodsmentioning

confidence: 99%

Induced pelletized growth of neurospora crassa for tyrosinase biosynthesis in airlift fermenters

Rajan¹,

Virkar²

1987

Biotech & Bioengineering

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Growth of filamentous fungi in conventional stirred tank fermenters is associated with many problems. The filamentous morphology of the biomass tends to make the system highly viscous and non-Newtonian in behavior resulting in a reduction in mixing and oxygen transfer rates. These have been quantified by Deindorfer and Gaden' for P . chrysogenum and by Steel and Brierly* for A . niger. Furthermore, the capacity of fungal mats to entrap air tends to make them float at the gas-liquid interface. In practice, the vigorous agitation used to overcome some of these problems, in addition to being energy intensive, can have a detrimental effect on shear sensitive biosystems. The tendency of the mycelial biomass to adhere to the internal surfaces and shaft of the fermenter poses additional operational problems, and makes harvesting and subsequent cleaning of the fermenter a cumbersome procedure. Most of these problems could be overcome if the fungus could be induced to grow as discrete spherical pellets. Various factors that affect the formation and growth of pellets have been reviewed by Metz and K~s s e n ,~ who also highlighted the role of surface active agents, both ionic and nonionic, in pelletization of fungal biomass. Gbewonyo and Wang4 have suggested the use of celite as a microporous inert carrier to confine the mycelial growth and form pellets. Martin and Bailey5 proposed a role for some as yet unidentified factors in peat extract, along with some additional nutrients, in pellet formation.In our laboratory, Neurospora crassa was induced to grow as discrete pellets by the addition of trace amounts of Triton N-101 (ethoxylated nonyl phenol) and used for the biosynthesis of tyrosinase enzyme in low-shear, aerated airlift fermenters. In addition to the pelletized growth of biomass, the efficacy of the system was judged by the ability of the fungus to form the product, which is synthesized as an intracellular secondary metabolite in response to the derepressing action of cycloheximide added during the stationary phase of fermentation." MATERIALS AND METHODSNeurospora crassa (IARI 1702 CCBS 709.71) was obtained from the Indian Agricultural Research Institute. A conidial suspension was prepared in sterile distilled water from stock cultures and used as an inoculum. Initial spore concentrations were (4.56) x 10% medium in the air-lift fermenter batches and (1.5-3) x 10VL for the shake flask cultures. The medium used was similar to that recommended by Horowitz and coworkers" with either sucrose or sugarcane molasses as the sole carbon source. The initial sugar concentration was adjusted to either 10 or 20 g/L. Full strength "Vogel's mediumh" was used as the source of nitrogen and mineral nutrients instead of the recommended halfstrength. For pelletization, ca. 100 ppm Triton N-101 was added to the medium in all the experiments reported here.Shake flask studies were carried out in 5-L conical flasks with 2 L medium on rotary shakers (100 strokedmin). Medium sterilization was achieved in situ as per standard practice. In t...

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“…29 Histidase activity was assayed according to the method of Tabor and Mehler 30 and was calculated using a molar extinction coefficient of 18,800 M 21 cm 21 for urocanic acid and expressed as nmol of urocanic acid formed/min/mg protein. Tyrosinase activity was measured according to the method of Horowitz et al 31 and a unit of activity was expressed as the amount of enzyme, which catalyzed the transformation of 1 nmol of substrate/min/mg protein.…”

Section: Biochemical Parametersmentioning

confidence: 99%

Correlation of DNA damage in epidemic dropsy patients to carcinogenic potential of argemone oil and isolated sanguinarine alkaloid in mice

Das

Ansari

Dhawan

et al. 2005

Intl Journal of Cancer

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In recent times, a higher incidence of gall bladder carcinoma in the Indo‐Gangetic basin has been linked with the consumption of contaminated mustard oil. Consumption of mustard oil contaminated with argemone oil (AO) is well known to cause clinical manifestation referred to as “epidemic dropsy.” Because sanguinarine, an active alkaloid of AO, has been shown to intercalate DNA, a possible correlation of DNA damage in epidemic dropsy patients to tumorigenic potential of AO and isolated sanguinarine alkaloid in mice was investigated in the present study. Single topical application of AO (0.15–0.3 ml) or isolated sanguinarine (4.5–18 μmol) followed by twice‐weekly application of tetradecanoylphorbolmyristate acetate (TPA) for 25 weeks resulted in formation of tumors. Histopathologically these tumors were of squamous cell carcinoma type and similar to those found in the positive control group using dimethylbenzanthracene (DMBA)/TPA. The activities of cutaneous γ‐glutamyl transpeptidase (GGT) and glutathione‐S‐transferase P (GST‐P), marker enzymes of tumorigenesis, were found to exhibit higher expression in AO or isolated sanguinarine/TPA treated groups when compared to control. The higher expression of p53 and p21/WAF1 in skin after single topical application of AO or isolated sanguinarine further confirms the tumorigenic response. Single topical application of AO or isolated sanguinarine alkaloid to mice showed significant DNA damage in terms of Olive tail moment (89–129%), tail length (54%) and tail DNA (153–205%) using Comet assay in skin cells. Further, the extent of DNA damage in blood cells of epidemic dropsy patients in alkaline Comet assay was found to be significantly higher as compared to normal population, indicating the genotoxic response of AO exposure. Although the genotoxic lesions may be repaired to some extent on withdrawal of consumption of AO contaminated mustard oil and the residual genotoxic effects caused by AO may not be expressed as signs of carcinogenesis. Environmental factors or hormonal changes during aging process may lead to stimulate/promote the genetically altered latent cells to form neoplastic lesions and can act as one of the etiological factors responsible for higher incidence of gall bladder carcinoma in the population of Indo‐Gangetic basin. © 2005 Wiley‐Liss, Inc.

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[77] Tyrosinase (Neurospora crassa)

Cited by 62 publications

References 7 publications

Purification and characterisation of phenoloxidase from amphioxus Branchiostoma belcheri tsingtauense

Purification and characterisation of phenoloxidase from amphioxus Branchiostoma belcheri tsingtauense

Induced pelletized growth of neurospora crassa for tyrosinase biosynthesis in airlift fermenters

Correlation of DNA damage in epidemic dropsy patients to carcinogenic potential of argemone oil and isolated sanguinarine alkaloid in mice

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