Results 181 to 190 of about 7,448 (206)

Study on Barley and Malt Polyphenoloxidase. I. Chromatography of Barley, Steeped Barley, and Malt Polyphenoloxidase

Journal of the American Society of Brewing Chemists, 1977
A comparative chromatography of polyphenoloxidase isolated from barley, steeped barley, and green malt was made.
N. Van Huynh, J. Jerumanis
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Strawberry Polyphenoloxidase: Purification and Characterization

Journal of Food Science, 1990
ABSTRACT Stable and highly active polyphenoloxidase (PPO) extracts were obtained using polyvinylpyrrolidone, Amberlite XAD‐4, Triton X‐100, and protease inhibitor in pH 5.25 buffer. Citrate and phosphate prevented binding of PPO to pectin.
PEDRO WESCHE‐EBELING, MORRIS W. MONTGOMERY   +1 more
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State of Copper in Polyphenoloxidase (Tyrosinase)

Nature, 1957
IT was shown in the classical work of Kubowitz1 and of Keilin and Mann2 that the prosthetic group of polyphenoloxidase is constituted by copper. Since then it has been unanimously admitted that the metal of the enzyme is in the bivalent state and that the catalytic activity of the enzyme is based on the change of valency cupric ⇌ cuprous, as follows ...
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Mini-chromatofocusing of plant and fungal polyphenoloxidases

Analytical Biochemistry, 1988
Mini-chromatofocusing was used to estimate the isoelectric points of mung bean polyphenoloxidase (5.4), broad bean polyphenoloxidase (5.4-5.7), and mushroom tyrosinase (4.5) in crude and purified samples. Using 1 to 2 ml of Polybuffer exchanger and 20 to 25 ml of Polybuffer 74, isoelectric points for the above enzymes were obtained in less than 2 h ...
B M, Moore, W H, Flurkey
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Maillard reaction products inhibit apple polyphenoloxidase

Food Chemistry, 1995
Abstract The effects of Maillard reaction products (MRP) on apple polyphenol oxidase (PPO) were evaluated spectrophotometrically at 400 nm after oxidation of 4-methylcatechol. MRP, synthesized under different conditions including heating time, type of amino acids, pH and concentration of both amino acid and glucose, showed different effects on apple ...
B.K. Tan, N.D. Harris
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Transient kinetic studies of dopa oxidation by polyphenoloxidase

Biochimica et Biophysica Acta (BBA) - Enzymology, 1971
The oxidation of DOPA (o-dihydroxyphenylalanine) to dopachrome as catalyzed by polyphenoloxidase (o-diphenol:O2 oxidoreductase, EC 1.10.3.1., also called tyrosinase) has been followed in transient-state experiments. The progress of the reaction depends on the wavelength of observation and in the spectral region where dopachrome is the major ...
D, Kertesz, M, Brunori, R, Zito, E, Antonini   +3 more
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EPR Spectroskopy of Dog-Rose Polyphenoloxidase

1997
Polyphenoloxidase(PPO) of dog-rose fruit was extracted and purified through (NH4)(2)SO4 precipitation and dialysis. The optimum conditions for this purpose, i.e., pH and temperature, were determined with 4-methylcatechol optimum pH and temperature and found to be pH 8.5 and 20 degrees C, respectively.
Kufrevioglu, I, NUHOGLU, C, Sakiroglu, Halis, YOGURTCU, YK, UCUN, F, AYYILDIZ, Eyüp   +5 more
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Characterization of Polyphenoloxidase from Stanley Plums

Journal of Food Science, 1992
ABSTRACT Five plum cultivars were investigated for polyphenoloxidase. Stanley cultivar, which showed highest PPO activity, was selected for characterization of this enzyme. The activity of crude enzyme was 3.5 times greater in the flesh than in the skin of the fruit. The enzyme showed a K m
M. SIDDIQ, N. K. SINHA, J. N. CASH
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Strawberry Polyphenoloxidase: Extraction and Partial Characterization

Journal of Food Science, 1990
ABSTRACT Mixing strawberries ground under liquid nitrogen with polyvinylpyrrolidone alone or combined with Amberlite XAD‐4 in pH 4.5 buffer yielded stable polyphenoloxidase (PPO) extracts. Temperature stability of the enzyme varied with substrate and followed first order kinetics of inactivation.
PEDRO WESCHE‐EBELING, MORRIS W. MONTGOMERY   +1 more
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Purification of polyphenoloxidase from coffee fruits

Food Chemistry, 2003
Abstract Polyphenoloxidase (PPO) was purified from coffee beans at the pinhead stage. Purification was carried out by precipitation of contaminating proteins with 30% (NH4)2SO4, dialysis of the supernatant and chromatography on phenyl sepharose and DEAE columns. A purification factor of 364 was obtained.
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