Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.10.3.1 (tyrosinase)
9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an attempt to determine the factors involved in ocular pigment variation, the eyes of pallid mice (c57BL/6J-Pa/Pa), and those of littermate black mice (C57BL/6J-+/Pa) were examined ultrastructurally, histochemically, and biochemically. As controls, the eyes of black and congenic albino mice (C57BL/6J +/C2J and -C2J/C2J) were also examined. In the developing pallid mouse eye the retinal pigment epithelium (RPE) and choroid contained immature melanosomes with incomplete melanization. In the adult pallid RPE, numerous lysosomal structures containing melanin components were present, while in choroid, melanosome numbers not only increased but many were aggregated in large membrane-bound granules. These RPE and choroidal structures may be melanolysosomes because of their histochemical acid phosphatase positive reactions. Biochemically, the activity of acid phosphatase in ocular homogenates of pallid eyes was significantly higher than in either the black eyes of +/Pa or in the albino and black eyes of the C2J genotypes. Dopa reactions at the light and electron microscopic levels indicated that Dopa oxidase activity was present in the cells of the RPE and choroid of both pallid and black mice. Histochemically the Dopa reaction of pallid pigment cells seemed to be equal to that of black ones, suggesting that tyrosinase production might be normal in pallid pigment cells. Biochemically, however, tyrosinase activity in the pallid eye was significantly lower than in the black control. It is concluded that the active digestion of melanosomes, as well as the low ocular tyrosinase activity and the immaturity of pallid melanosomes, may contribute to the pigment dilution observed in the pallid mouse eye.
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PMID:Ultrastructural, histochemical and biochemical studies of the melanin metabolism in pallid mouse eye. 712 80

In the pigment cells of the white mutant of Drosophila melanogaster, as described earlier, two types of abnormal granules are found by conventional electron microscopy. However, both types of abnormal granules, in addition to those in pigment cell invaginations, are also present in the cytoplasm of the photoreceptor cells. Three enzymes (acid phosphatase, peroxidase, and tyrosinase) are localized within the eyes of wild type and white mutant Drosophila melanogaster by electron microscopy. Peroxidase activity is present in lamellar bodies close to the rhabdomeral microvilli of both fly types. However the organelles containing peroxidase activity are 6-fold more frequent in the wild type than in the mutant. Acid phosphatase is present in lamellar bodies between and at the bases of the rhabdomeral microvilli of the wild type, as well as in ommochrome granules of the photoreceptor cells. In the white mutant, however, acid phosphatase was located in electron lucent vacuoles in the cytoplasm of the receptor cells. These acid phosphatase-positive vacuoles also contained both types of abnormal granules. The latter result indicates that abnormal granules in the receptor cells originate from lysosomal degradation and that targeting of lysosomal enzymes is altered in the white mutant. Due to the tyrosinase activity in the hemolymph of flies, the extracellular spaces are electron dense after DOPA incubation. Since some abnormal granules within the photoreceptor cells are not surrounded by an extracellular space, they can be assumed to originate within the photoreceptor cells.
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PMID:Atypical granules in the eyes of the white mutant of Drosophila melanogaster are lysosome-related organelles. 839 98

The hair follicles exhibit an intrinsic hair cycle that is divided into three phases; growth (anagen), transition (catagen) and quiescence (telogen). To make sure of the effects on hair growth by chemical substances, we should evaluate the induction of the anagen phase and/or elongation of the anagen period and delay in catagen separately, but the regulatory mechanism of the hair cycle is unclear. We have investigated the levels of biochemical markers in the third hair cycle period of C3H mouse (8 weeks, male) after depilation and compared them with those in a non-treated group. The dorsal areas (2 cm x 4 cm) were clipped and depilated with hair remover. The dorsal skin samples were collected 1, 8, 11, 15 and 18 days after depilation and the levels of biochemical markers, i.e. skin transglutaminase, skin sulfhydryl oxidase, cathepsin D, gamma-glutamyl transpeptidase, alkaline phosphatase, acid phosphatase, tyrosinase activities and histamine content in each skin sample were examined. The levels of gamma-glutamyl transpeptidase, tyrosinase and alkaline phosphatase were relevant to hair re-growth in the control group, but not skin transglutaminase, skin sulfhydryl oxidase, cathepsin D activities. The histamine content increased just after depilation treatment and returned to the normal level within two weeks, compared with the non-treated group. All these results suggest that the markers examined in this C3H mice model are useful for studying the distinctive process of hair re-growth caused by active substances.
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PMID:Evaluation of biochemical indices as a hair cycle marker in C3H mice. 884 Jan 42

In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome. Granules having a homogeneous matrix also function as premelanosomes. The presence of acid phosphatase reaction product inside the melanin granules indicated that these organelles in this animal were also related to lysosomes. DOPA-oxidase of tyrosinase, the key enzyme in melanogenesis, was surprisingly not only detected in melanocytes but also in the Golgi stacks of dermal cells. Due to the mechanisms of premelanosome formation it is evident that cytoplasmic material also serves as substrate for melanogenesis. EDX microanalysis was performed to measure the ionic composition of the melanin granules. After aldehyde fixation the newly-formed melanin granules did not contain Na, but had accumulated Ca.
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PMID:Heterogeneous ultrastructure of melanosome formation in the goldfish induced by osmotic stress. 886 53

Vitiligo is a common dermatological disorder characterized by the development of complete pigment loss from focal lesions that tends to increase in size over time. The etiology of vitiligo, resulting in the disappearance of functional melanocytes from involved skin, is not clearly understood. As a consequence, no satisfactory therapy has been developed. A subtype of vitiligo, termed 'occupational' or 'contact' vitiligo, is increased in individuals who are exposed to materials containing phenolic derivatives, such as 4-tertiary butylphenol (4-TBP). Phenolic derivatives are structurally similar to tyrosine, the initial substrate of tyrosinase in the biochemical synthesis of melanin. Therefore, it has been proposed that phenolic derivatives compete with tyrosine for hydroxylation by tyrosinase and interfere with the completion of melanin synthesis and/or generate cytotoxic intermediates. Our results demonstrated that 4-TBP competitively inhibited both tyrosine hydroxylase and dihydroxyphenylalanine (DOPA) oxidase activities of tyrosinase, i.e., the first two catalytic steps in the biochemical conversion of tyrosine to melanin in cultured human melanocytes. This inhibition occurred at concentrations that did not influence the viability of melanocytes. The tyrosinase activity inhibited by 4-TBP was recovered after removing the treatment. 4-TBP did not affect the function of other enzymes, such as succinate-tetrazolium reductase, acid phosphatase and sulfatase. Since depigmentation occurred without a cytotoxic response after exposure of melanocytes to low concentration of 4-TBP, it is unclear whether the interaction between 4-TBP and tyrosinase leads to the destruction of the melanocytes in 'contact/occupational' vitiligo.
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PMID:Effects of 4-tertiary butylphenol on the tyrosinase activity in human melanocytes. 1045 91

Molecular characterisation of clonal apple rootstocks using isozymes was carried out to identify isozyme polymorphism in seven clonal apple rootstocks and to identify the most characteristic and stable enzyme markers for each individual rootstock. Five enzyme systems were studied out of which polyphenol oxidase, malate dehydrogenase, acid phosphatase and peroxidase were useful in discriminating among the rootstocks. The peroxidase enzyme system showed maximum variation and esterase showed the least variation among the rootstocks. Out of seven rootstocks, three were distinguished on the basis of one enzyme system only (M.3 with MDH or PER, M.7 with PPO or PER and MM. 111 with MDH). Out of the sixteen loci studied seven were found to be polymorphic. Genetic variation among the rootstocks was explained on the basis of various parameters. The percentage of polymorphic loci varied from 13.33 to 35.71 per cent.
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PMID:Distinguishing clonal apple rootstocks by isozymes banding patterns. 1190 9

Allozyme spectra of peroxidase, esterase, superoxid dismutase, tyrosinase, alcohol dehydrogenase, lactate dehydrogenase, and acid phosphatase were examined in populations of sexual (Taraxacum serotinum and Pilosella echioides) and apomictic (T. officinalis and P. officinarum) plant species. The heterozygosity in these populations (0.455-0.620) proved to be considerably higher than the average level characteristic of plant populations (0.058-0.185). The populations examined did not differ in the mean phenotype number mu, i.e., they exhibited the same diversity (3.213-3.380). The proportion of rare phenotypes h also did not differ between the sexual and apomictic species of the same genus, whereas this parameter in the Pilosella populations (0.150-0.174) was significantly higher than in the Taraxacum ones (0.093-0.114). The populations were characterized by numerous isozyme spectra (more than 11 per populations) and displayed multiple allelism (the mean allele frequency was 3.63-4.38 per locus). They exhibited a high percentage of rare (occurring at a frequency lower than 5%) spectra (35-80%). This indicates that agamic complexes, to which these populations belong, may have a more complicated genetic structure of both apomictic and sexual populations than the species that do not belong to agamic complexes.
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PMID:[Allozyme variation in sexual and apomictic Taraxacum and Pilosella (Asteraceae) populations]. 1581 Jun 10

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder resulting from mutations in a family of genes required for efficient transport of lysosomal-related proteins from the trans-Golgi network to a target organelle. To date, there are several genetically distinct forms of HPS. Many forms of HPS exhibit aberrant trafficking of melanosome-targeted proteins resulting in incomplete melanosome biogenesis responsible for oculocutaneous albinism observed in patients. In HPS-1, melanosome-targeted proteins are localized to characteristic membranous complexes, which have morphologic similarities to macroautophagosomes. In this report, we evaluated the hypothesis that HPS-1-specific membranous complexes comprise a component of the lysosomal compartment of melanocytes. Using indirect immunofluorescence, an increase in co-localization of misrouted tyrosinase with cathepsin-L, a lysosomal cysteine protease, occurred in HPS-1 melanocytes. In addition, ribophorin II, an integral endoplasmic reticulum protein that is also a component of macroautophagosomes, and LC3, a specific marker of macrophagosomes, demonstrated localization to membranous complexes in HPS-1 melanocytes. At the electron microscopic level, the membranous complexes exhibited acid phosphatase activity and localization of exogenously supplied horseradish peroxidase (HRP)-conjugated gold particles, indicating incorporation of lysosomal and endosomal components to membranous complexes, respectively. These results confirm that membranous complexes of HPS-1 melanocytes are macroautophagosomal representatives of the lysosomal compartment.
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PMID:Membranous complexes characteristic of melanocytes derived from patients with Hermansky-Pudlak syndrome type 1 are macroautophagosomal entities of the lysosomal compartment. 1628 7

An original amperometric biosensor based on the simultaneous entrapment of acid phosphatase (AcP) and polyphenol oxidase (PPO) into anionic clays (layered double hydroxides) was developed for the specific detection of As(V). The functioning principle of the bienzyme electrode consisted of the successive hydrolysis of phenyl phosphate into phenol by AcP, followed by the oxidation of phenol into o-quinone by PPO. The phenyl phosphate concentration was, thus, monitored by potentiostating the biosensor at -0.2 V vs Ag/AgCl to detect amperometrically the generated quinone. The detection of As(V) was based on its inhibitory effect on AcP activity toward the hydrolysis of phenyl phosphate into phenol. The As(V) can be specifically determined in pH 6.0 acetate buffer without any interferences of As(III) or phosphate, the detection limit being 2 nM or 0.15 ppb after an incubation step for 20 min.
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PMID:Specific determination of As(V) by an acid phosphatase-polyphenol oxidase biosensor. 1684 21

In a pot experiment, the aqueous extract of 10 years old Zanthoxylum bungeanum's leaves was used to water Z. bungeanum seedlings to test its effects on soil microbes and enzyme activities. The results showed that the leaf extract decreased the total amount of microbes and the quantity of bacteria, fungi and actinomyces in rhizosphere soil, but increased the total amount of microbes in non-rhizosphere soil. After watering with the extract, the proteinase, invertase and acid phosphatase activities in rhizosphere soil were considerably lower than those in nonrhizosphere soil, while catalase and polyphenol oxidase activities were in adverse. Soil proteinase activity had a significant positive correlation with invertase activity, but a significant negative correlation with actinomyces amount. Soil polyphenol oxidase activity had a significant negative correlation with invertase activity, but a positive correlation with the total amount of microbes and the quantity of bacteria, fungi and actinomyces. Soil actinomyces only had significant correlations with proteinase, polyphenol oxidase and invertase activities and fungi.
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PMID:[Effects of Zanthoxylum bungeanum leaf extract on soil microbe quantity and enzyme activities]. 1714 75


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