Results 221 to 230 of about 8,233 (250)

High Pressure Inactivation of Polyphenoloxidases

Journal of Food Science, 1998
ABSTRACT Pressure stabilities of polyphenoloxidases (PPO) from apples, avocados, grapes, pears and plums were determined at pH 6‐7. These PPOs differed in pressure stability, but all were rather pressure‐stable. Inactivation of PPO from apple, grape, avocado and pear at room temperature (25°C) became noticeable at
C. WEEMAES, L. LUDIKHUYZE, I. VAN DEN BROECK, M. HENDRICKX   +3 more
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Inhibition of Polyphenoloxidase by Sulfite

Journal of Food Science, 1986
ABSTRACT When polyphenoloxidase (PPO) was exposed to sulfite prior to susbstrate addition, inhibition was irreversible. Trials to regenerate PPO activity, using extensive dialysis, column chromatography, and addition of copper salts were not successful. Increased concentrations of sulfite and pH levels less than 5
L. A. SAYAVEDRA‐SOTO, M. W. MONTGOMERY
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Properties of carrot polyphenoloxidase

Phytochemistry, 1995
A latent phenoloxidase (PPO) was purified in the presence of protease inhibitors from carrot cells to electrophoretic homogeneity. The inactive enzyme had a M(r) of ca 59 000 under denaturating conditions as judged by SDS-PAGE. When stored in the absence of protease inhibitors, PPO in a crude extract was converted to forms with a lower M(r).
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Inhibition of Banana Polyphenoloxidase by 2-Mercaptobenzothiazole

Science, 1967
2-Mercaptobenzothiazole is an exceptionally potent inhibitor of banana polyphenoloxidase; it significantly delays the onset of substrate oxidation at concentrations as low as 10 -7 M and causes prolonged inhibition at 2 × 10 -5 M or higher.
J K, Palmer, J B, Roberts
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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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