Pectin-polygalacturonase PG

Measurement of the increase in reducing power (free aldehyde groups) by the Willstatter-Schudel hypoiodite method and its modifications is still the most popular method for following PG action. This method permits a high degree of accuracy in the latter stages of hydrolysis but it 

Part of this objection to the calcium pectate as a means of following the hydrolysis of pectic materials can be met by using the simple procedure developed by Fellers and Rice for the estimation of pectic substances as pectic acid. This approximate method measures the volume of the pectic acid which can be produced from a sample of soluble pectic material and will therefore show the loss of colloidality by the rapidly decreasing volume even if the weight of the precipitate remains the same. Unfortunately the Fellers-Rice method is not sufficiently accurate for exact kinetic studies. 

Many physical methods of measurement have been applied in follow- 

It may be added that viscosity measurements have often been applied for the evaluation of the PG in commercial pectinases.8 This method, as will be seen below, might give dependable results under certain conditions but, due to the many complicating factors, it should be carefully adjusted before too much trust is placed in the results. 

Recently Matus39 found that PG was entirely without action on the (neutral) glycol ester of pectic acid. As the extent of esterification was reduced, PG showed increasing activity. 

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Bussink et al. [4] and Kusters-van Someren et al. [5] have shown that in A. niger for both polygalacturonases (PGs) and pectin lyases (PLs) families of genes are present seven... 

Figure 1. Time-course measurement of polygalacturonase (PG) activity in the culture filtrate of Colletotrichum lindemuthianum grown on pectin and HPLC-Dionex analysis of mono-, di- and tri-galacturonic acid residues simultaneously released in the culture medium. The data are the mean of three independent experiments or represent one typical experiment in the case of galacturonic acid (GalA) residues. DP= Galacturonic acid degree of polymerization.

The purified enzyme could hydrolyze pectin and sodium pectate. However, the absorbancy at 253 nm and pH of the reaction mixture were not changed. The purified enzyme showed the activity to be polymethyl-galacturonase (PMG)and polygalacturonase (PG). 

The catalytic capacity of several excreting pectolytic enzymes obtained from various yeast strains was examined using in vivo and biochemical techniques. Of the 33 yeast strains studied 30 were isolated from champagne wine during alcoholic fermentation. Only one yeast strain was found to excrete pectolytic enzymes and was identified as Saccharomyces cerevisiae designated SCPP. Three types of pectolytic enzymes were found to be excreted by SCPP polygalacturonase (PG), pectin-lyase (PL) and pectin-esterase (PE) [1]. 

Enzyme.—Polygalacturonase (PG) was obtained from a culture of Rhizopus nigricans using Citrus pectin as carbon source [11,12], The enzyme used for oligouronides obtention was the residual activity after a thermal treatment (100°C, 60 sec) of the native Rh. nigricans endo and exoPG, since the endo-enzyme was thermoresistant while the exo-enzyme was thermolabile [13]. 

Tomato Zeneca/1994 A fragment of the polygalacturonase (PG) gene to suppress the endogenous PG enzyme Tomato Delayed softening due to reduced pectin degradation... 

Giner-Segui et al. (2006) studied the evolution of polygalacturonase (PG) (EC 3.2.1.15) activity in aqueous solution of commercial enzyme preparation. Up to 76.5% reduction of the PG activity could be achieved at 38 kV cm and 1100 J,s EF intensity and treatment time, respectively. However, an enhancement of PG activity at soft PEF treatment conditions (up to 110.9% at = 15kV cm and 300 J,s) was observed. A maximum of 80% of pectin methyl esterase activity in orange juice was inactivated at 35 kV cm and 1500 J,s EF strength and treatment time, respectively (Elez-Martinez et al., 2007). 

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