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Polygalacturonase of Erwinia carotovora
The polygalacturonase, clearly differentiated from polygalacturonic acid trans -eliminase, produced in the culture fluid of Erwinia carotovora was purified 56-fold by means of acetone precipitation, acetate buffer extraction, and two successive treatments by chromatography on carboxymethyl cellulose...
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Published in: | The Journal of biological chemistry 1966-11, Vol.241 (22), p.5298-5306 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The polygalacturonase, clearly differentiated from polygalacturonic acid trans -eliminase, produced in the culture fluid of Erwinia carotovora was purified 56-fold by means of acetone precipitation, acetate buffer extraction, and two successive treatments by chromatography
on carboxymethyl cellulose. The purified enzyme is specific for nonmethoxylated polygalacturonic acid. It shows an optimum
pH between 5.2 and 5.4; no shift of optimum pH is observed when tetragalacturonic acid is used as a substrate. The activity
is stimulated by 0.1 m sodium, potassium, and ammonium ions, but not by 0.001 m calcium, magnesium, and barium ions. At 0.1 m , phosphate (pH 5.2), chloride, and sulfate ions are somewhat inhibitory as compared to acetate ions, but 0.1 m phosphate (pH 4.8) and 0.001 m polymetaphosphate ions are not inhibitory.
The major end products are mono- and digalacturonic acids. Digalacturonic acid is not hydrolyzed further. The relative initial
rates of the reactions on substrates of different chain lengths are: polygalacturonic acid, 100; shorter chain polygalacturonic
acid (average degree of polymerization, 12), 52; hexagalacturonic acid, 15.8; pentagalacturonic acid, 12.8; tetragalacturonic
acid, 2.2; trigalacturonic acid, 1.7. Hexamer is cleaved predominantly at the central bond, producing 2 molecules of trimer;
slower reactions yielding dimer and tetramer were also observed. Pentamer is cleaved only into dimer and trimer. Tetramer
is cleaved at Bond 1 to yield trimer and monomer; the central bond of tetramer is also cleaved at a lower but significant
rate to form dimer. Both reduced and oxidized tetramer are cleaved much more slowly, and at the central bond only, resulting
in an accumulation of normal and reduced or oxidized dimer. Simultaneous attack of Bonds 1 and 2 is postulated for trimer
hydrolysis, since only the monomer is found as the reaction product and no dimer is detected, although Erwinia polygalacturonase cannot hydrolyze the dimer. Both reduced and oxidized trimer are cleaved at Bond 1 after a long incubation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)96430-6 |