The ability of a number of mesoporous silica materials (SBA-15, SBA-3, and MCM-48) to immobilize polyphenol oxidase (PPO) at different pH has been tested. Pore size and volume are the structural characteristics with higher influence on the PPO immobilization. Mesoropous material SBA-15 adsorbs a larger quantity of PPO at pH 4.00 and offers an inhibition of enzymatic activity close the 50% in ap...

-Aqueous acetone extracts of shoots of Eurasian watermilfoil (Myriophyllum spicatum) exhibit a strong inhibitory action against various coccoid and filamentous cyanobacteria and to a slightly less extent against chlorophytes and diatoms. Bioassay-directed fractionation led to the isolation of a hydrolysable polyphenol, tellimagrandin II, which turned out to be the main inhibitory substance. Myr...

A study of the catecholase activity of a latent plant polyphenol oxidase, extracted and purified from the chloroplast membranes of grapes (Vitis vinifera cv. Airen), revealed for the first time a lag phase above pH 5.0, whereas a steady-state rate was reached immediately when pH values were lower, thus suggesting the hysteretic nature of the enzyme. During steady state, the enzyme showed negati...

In the course of a study of the enzymes of Piricularia oryzae Cav., the fungus causing the blast disease of rice, it was observed that activity of crude polyphenoloxidase preparations from culture filtrates was not inhibited by sodium diethyldithiocarbamate (DEDTC), a widely used inhibitor of copper-containing enzymes. Further investigation revealed that such preparations contained an enzyme wh...

Herein, we present three new binuclear copper(II) complexes containing different polycyclic aromatic hydrocarbons, able to catalyze the oxidation of 3,5-di-tert-butylcathecol, a model substrate for catechol oxidase. The ligands and were successful characterized in solid solution states. structure C1 was determined by X-ray crystallography it contains [CuII2(L1-?-phenoxo)(OAc)(H2O)2] unit, with ...

Soils contaminated with low levels of heavy metals and other trace elements are now frequently used for vegetable growing. In this situation, heavy metals and trace elements from these polluted soils may accumulate in the agricultural plants being grown in them and thereby enter the human food chain. The objectives of this study are to elucidate the effects of growth conditions, manipulated by ...

Black pepper (Piper nigrum L.) is the most widely used spice in the world. Blackening is considered to be beneficial and important in the processing of black pepper because it contributes to its color and flavor. The purpose of this paper is to investigate polyphenol oxidation as well as the chlorophyll and vitamin C (VC) degradation in the blackening of Piper nigrum L. Black pepper was produce...

The aim of this study was to evaluate the effects of foliar application of boron and calcium on postharvest storage characteristics of Asian pear (Pyrus pyrifolia) fruit. This experiment was carried out in the experimental orchard of Asian pear at Tarbiat Modares University, Tehran, Iran. The treatments were two concentrations of boric acid (0% and 0.5%) and three concentrations of calcium chlo...

Received: December 28, 2013; Revised; January 25, 2014; Accepted: March 2, 2014 . Abstract: A major problem in the micro propagation of litchi is the secretion of polyphenols into the medium by the tissues once excised. This secretion undergoes oxidation to produce substances that kill the tissues. The first visual symptom of deterioration is skin browning which has been reported to appear due ...

Tyrosinases are type 3 copper enzymes that belong to the polyphenol oxidase (PPO) family and are able to catalyze both the ortho-hydroxylation of monophenols and their subsequent oxidation to o-quinones, which are precursors for the biosynthesis of colouring substances such as melanin. The first plant pro-tyrosinase from Malus domestica (MdPPO1) was recombinantly expressed in its latent form (5...