Oligogalacturonates

Bromophenol blue (3.0...4.6) aliphatic carboxylic acids [225 — 228] malonic and lactic acids [229] palmitic and lactic acids [230] malonic, glycolic, malic, citric, tartaric, ketoglutaric, galacturonic and oxalic acids [196] dicarboxylic acids, succinic acid [231] indoleacetic acid, trichloroacetic acid [232] palmitic acid, palmityl- and stearyllactic acid [223] benzoic, sorbic and salicylic acid [234] metabolites of ascorbic acid [235] chloropropionic acid [236] oligogalacturonic acids [237] amino acids, hydrocarbons, mono-, di- and triglycerides [238] xylobiose, xylose, glucose and derivatives [239] sugar alcohols [91] toxaphene [240]... 

Ochratoxin A 69,147,166,167 Oieanolic acid 59,60 Oleanonic acid 59,60,70 -, methyl ester 70 Olefins 359 Oleic acid 73, 89 Oligogalacturonic acids 45, 322 Oligonucleotides 76... 

Endo-polygalacturonases I and II (PGI and PGII) isolated from recombinant A. niger were characterized with respect to pH optimum, activity on polygalacturonic acid (pga), mode of action and kinetics on oligogalacturonates. 

Figure 1. HPLC analysis of product progression during hydrolysis of 0.25 % polygalacturonate by PGII. Aliquots were withdrawn from the reaction mixture at timed intervals and reactions were stopped by raising the pH of the sample to pH 8.0 by mixing with 1 volume 25 mM Na-phosphate pH 9.5. Gl to G5 indicate the oligogalacturonates with corresponding degree of polymerization. The vertical axis shows the responce of the pulsed amperometric detector and the horizontal axis the elution time. Times of sampling are indicated above the trace.

Table I. Mode of action of PGII. Bond cleavage frequencies (BCF) in percentage for oligogalacturonates. The reducing or end of the products is indicated with a solid circle. The position of cleavage is indicated with a solid triangle.

In order to estimate the number of subsites, the binding affinities, the location of the active site and the cleavage patterns reduced and non reduced oligogalacturonates of DP 4 to 6 were used as substrates and the resulting products analysed by HPLC and TLC. 

Figure 5. Selected HPLC elution profile of products obtained after incubation of 0.25% polygalacturonate with PGII, upper trace, and PGII H223A, lower trace, respectively, demonstrating the effect of the mutation on catalysis. G1 to G3 indicate the peaks of the corresponding oligogalacturonates. IS indicates the internal standard, glucuronate. The vertical axis shows the pulsed amperometric detector response while the horizontal axis shows the retention time.

The Michaelis constant (Km) and the maximum rate (Fmax) of PGX for PGA, reduced and non-reduced oligogalacturonates with increasing degree of polymerization (DP=2-7) were determined. Data are presented in Table 2. 

Kinetic parameters of A. tubingensis PGX for nonreduced and reduced oligogalacturonates and polygalacturonic acid. 

Figure 5. HPLC profiles of products from reactions catalyzed by secreted pectate lyase activities from Erwinia chrysanthemi after 66 min and 192 min. Reaction mixtures contained 4 units of enzyme activity per ml and 0.1% PGA in 0.05 M Tris-HCl, pH 8.5, 0.2 mM CaClg. Injections of 0.05 ml were made from reaction mixtures with a WISP automatic sample injector and eluted at 2.0 ml/min with a run time of 60 min. Compounds eluting with retention times of 5.36, 6.40, 7.76, and 9.56 min corresponded to unsaturated oligogalacturonate reference standards with DP values of 2, 3, 4, and 5, respectively.

Figure 1. Normalized ellipticity at 210 nm as a function of the degree of neutralization (o ) for (1) sodium form of oligogalacturonates and polygalac-turonate (2) calcium form of galacturonates (O DP2, A DP4, DP5), (3) calcium form of the polygalacturonate (Ae taken as reference is the ellipticity of acid forms for each product open = sodium form filled = calcium form.)...

The rate of decomposition of O-trimethylsilyl derivatives of a series of oligogalacturonic acids has been studied 170 it was found that the rate increases with the degree of polymerization, but that the methyl esters decay about 55 times as slowly. 

Uronic acids have been studied similarly in connection with pectins384,523 and oligogalacturonic acids,170 fruits,319 and plants.66"524 Neukom and coworkers have studied the behavior of uronic acid and also aldaric acid derivatives.525 Ascorbic acid and its analogs526 have been separated by gas-liquid chromatography and determined291 in plant extracts. 

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