Starch Degradation in Spinach Leaves: ISOLATION AND CHARACTERIZATION OF THE AMYLASES AND R-ENZYME OF SPINACH LEAVES.

摘要: The properties of two amylase activities which differ in their substrate specificity and subcellular location as well a chloroplast-associated R-enzyme (debranching activity) are reported. An extrachloroplastic is resolved by gel filtration chromatography into 80,000 40,000 daltons. Both hydrolyze amylopectin shellfish glycogen only slowly rabbit liver glycogen, β-limit amylopectin, amylose. In contrast, the major chloroplastic attacks all these glucans at comparable rates. Glucan hydrolysis both generates not maltose but appreciable amounts other oligosaccharides, whereas maltotetraose produces glucose, maltose, maltotriose. action patterns displayed indicate that endoamylases, although they lack typical Ca 2+ requirement or heat stability seed endosperm α-amylases. Dithiothreitol, glutathione (oxidized reduced), ascorbate, dehydroascorbate, dithiothreitol plus thioredoxin have no effect on either activities. debranches pullulan, α-limit dextrins, glycogen. increase extinction coefficient λ max detected when debranched form complex with I 2 -KI. Based properties, similar enzymic activity to observed tissue.