Purification and properties of a high-molecular-weight, alkaline exopolygalacturonase from a strain of Bacillus.
1An exopolygalacturonase [exo-PG; poly (1,4-alpha-D-galacturonide) digalacturonohydrolase, EC 3.2.1.82] was found in a culture of Bacillus sp. strain KSM-P576. The purified exo-PG had a molecular weight of approximately 115,000 and an isoelectric point of pH 4.6. The N-terminal amino acid sequence was Thr-Glu-Val-Ser-Pro-Lys-Ser-Pro-Ala-Ser-Pro-Val. Maximum activity toward polygalacturonic acid (PGA) was observed at 55 degrees C and pH 8.0 in 100 mM Tris-HCl buffer. The exo-PG was quite stable in various pH buffers between pH 6 and 12 when incubated at 30 degrees C for 1 h. Mg(2+,) Mn(2+,) Pd(2+) and Ca(2+) ions stimulated the enzyme activity. The exo-PG released digalacturonic acid from PGA, tri-, tetra-, and penta-galacturonic acids. The apparent K(m) values for oligogalacturonic acids were almost identical, and k(cat) values increased with the chain length of the substrates.
Kobayashi
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Tochigi Research Laboratories of Kao Corporation, 2606 Akabane, Ichikai, Haga, 321-3497, Tochigi, Japan
Higaki
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N
Suzumatsu
A
A
Sawada
K
K
Hagihara
H
H
Kawai
S
S
Ito
S
S