Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using L-DOPA as a probe, phenoloxidase (PO) from Penaeus chinensis hemolymph was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular weight and enzymatic properties in this study. It was found that prophenoloxidase (proPO) isolated as monomeric protein had a molecular weight of 87.5 kD, and a 77 kD phenoloxidase molecule was often contained in preparations. The 87.5 kD proPO had a very low enzymatic activity on 0.02 mmol/L L-DOPA, whereas the 77 kD PO had a very high enzymatic activity on L-DOPA. Enzymatic activity of PO against L-DOPA was optimal at pH 6.0, temperature of 40 degrees, and with an apparent K(m) value of 1.99 mmol/L. The PO activity was extremely sensitive to ascorbic acid, cysteine and dithiothreitol, very sensitive to thio urea, however not sensitive to sodium sulfite, citric acid and benzoic acid, confirmed that it was a phenoloxidase, combined with its specific oxidase activity on substrate of monophenol and L-DOPA, indicate that it was a tyrosinase type phenoloxidase. This enzyme is very sensitive to EDTA and metal ions, its activity is strongly enhanced by Mg(2+) and strongly inhibited by Cu(2+), which indicates that this PO is probably a kind of metalloenzyme.
Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (Shanghai) 2002 Sep
PMID:[Purification and partial biochemical characterization of phenoloxidase from Penaeus chinensis]. 1219 61

Primary dark tea is used as raw material for compressed dark tea, such as Fu brick tea, Hei brick tea, Hua brick tea, and Qianliang tea. Pile-fermentation is the key process for the formation of the characteristic properties of primary dark tea, during which the microorganism plays an important role. In this study, the changes of major chemical compounds, enzyme activities, microbial diversity, and their correlations were explored during the pile-fermentation process. Our chemical and enzymatic analysis showed that the contents of the major compounds were decreased, while the activities of polyphenol oxidase, cellulase, and pectinase were increased during this process, except peroxidase activity that could not be generated from microbial communities in primary dark tea. The genera Cyberlindnera, Aspergillus, Uwebraunia, and Unclassified Pleosporales of fungus and Klebsiella, Lactobacillus of bacteria were predominant in the early stage of the process, but only Cyberlindnera and Klebsiella were still dominated in the late stage and maintained a relatively constant until the end of the process. The amino acid was identified as the important abiotic factor in shaping the microbial community structure of primary dark tea ecosystem. Network analysis revealed that the microbial taxa were grouped into five modules and seven keystone taxa were identified. Most of the dominant genera were mainly distributed into module III, which indicated that this module was important for the pile-fermentation process of primary dark tea. In addition, bidirectional orthogonal partial least squares (O2PLS) analysis revealed that the fungi made more contributions to the formation of the characteristic properties of primary dark tea than bacteria during the pile-fermentation process. Furthermore, 10 microbial genera including Cyberlindnera, Aspergillus, Eurotium, Uwebraunia, Debaryomyces, Lophiostoma, Peltaster, Klebsiella, Aurantimonas, and Methylobacterium were identified as core functional genera for the pile-fermentation of primary dark tea. This study provides useful information for improving our understanding on the formation mechanism of the characteristic properties of primary dark tea during the pile-fermentation process.
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PMID:Biochemical Components Associated With Microbial Community Shift During the Pile-Fermentation of Primary Dark Tea. 3004 50