Carbohydrate composition and electrophoretic properties of tomato polygalacturonase isoenzymes.
Two polygalacturonase isoenzymes, PG I and PG II, were extracted from Murrieta tomato and purified by gel exclusion and ion-exchange chromatography. The kinetic constants and activation energies of the purified isoenzymes have been determined. Polygalacturonase I has two polypeptide chains (Mr = 47 500 and 41 400) whereas polygalacturonase II is a single polypeptide (Mr = 47 500) as shown by electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulphate. Both isoenzymes are glycoproteins. Through gas liquid chromatography, polygalacturonase II was shown to contain 4.6% neutral hexoses and 1.5% amino sugars. There are eight D-mannose, two L-fucose, two D-xylose and three N-acetylglucosamine residues per mole of PG II. The carbohydrate portion of PG II was shown to be attached to the protein part through an N-acetylglucosaminylasparaginyl bond.
D002241:Carbohydrates / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D004586:Electrophoresis / Q000379:methods; D006026:Glycoside Hydrolases / Q000302:isolation & purification*; D007527:Isoenzymes / Q000302:isolation & purification*; D007700:Kinetics; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology*; D011096:Polygalacturonase / Q000302:isolation & purification*
D002241:Carbohydrates; D007527:Isoenzymes; D006026:Glycoside Hydrolases; D011096:Polygalacturonase