Document Detail

An exo-poly-alpha-D-galacturonosidase implicated in the regulation of extracellular pectate lyase production in Erwinia chrysanthemi.
MedLine Citation:
PMID:  7056698     Owner:  NLM     Status:  MEDLINE    
Pectic enzymes in the supernatants of Erwinia chrysanthemi cultures in late-logarithmic-phase growth on D-galacturonan were resolved into three components: two pectate lyase isozymes and an exo-poly-alpha-D-galacturonosidase previously unreported in this organism. The hydrolytic enzyme was purified to homogeneity by ammonium sulfate fractionation, preparative electrofocusing in Ultrodex gel, and gel filtration through Ultrogel AcA54. The enzyme had a specific activity of 591 mumol/min per mg of protein, a pI of 8.3, a molecular weight of 67,000, a pH optimum of 6.0, and a Km of 0.05 mM for D-galacturonan. Analyses of reaction mixtures by paper chromatography revealed that the enzyme released only digalacturonic acid from D-galacturonan. The action of the hydrolytic enzyme on D-galacturonan labeled at the nonreducing end by partial digestion with pectate lyase revealed that it rapidly released 4,5-unsaturated digalacturonic acid from 4,5-unsaturated pectic polymers. The production of extracellular exo-poly-alpha-D-galacturonosidase was coordinately regulated with pectate lyase production. The action patterns of the two enzymes appeared complementary in the degradation of pectic polymers to disaccharides that stimulated pectic enzyme production and supported bacterial growth.
A Collmer; C H Whalen; S V Beer; D F Bateman
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of bacteriology     Volume:  149     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  1982 Feb 
Date Detail:
Created Date:  1982-04-20     Completed Date:  1982-04-20     Revised Date:  2010-09-10    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  626-34     Citation Subset:  IM    
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MeSH Terms
Erwinia / enzymology*
Glycoside Hydrolases / metabolism*
Hydrogen-Ion Concentration
Isoenzymes / metabolism*
Molecular Weight
Pectins / metabolism
Polygalacturonase / metabolism*
Polysaccharide-Lyases / metabolism*
Reg. No./Substance:
0/Isoenzymes; 0/Pectins; 9046-38-2/polygalacturonic acid; EC 3.2.1.-/Glycoside Hydrolases; EC; EC 4.2.2.-/Polysaccharide-Lyases; EC lyase

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