Phosphoglucose isomerase from bananas: partial characterization and relation to main changes in carbohydrate composition during ripening.
Some characteristics of phosphoglucose isomerase (PGI, EC 5.3.1.9) from banana were measured during fruit ripening of three banana cultivars. In banana, PGI was present as two dimeric isoenzymes, named PGI1 and PGI2, which had similar native molecular masses but differed in relation to heat stability and isoelectric point. Total PGI activity showed a distinct two-step change during fruit ripening. Before the climacteric period, PGI activity gradually decreased with the starch content, then its activity began to increase with sucrose accumulation. The ratio of PGI1, and PGI2 was constant, indicating that both enzymes would be involved in starch degradation and sucrose synthesis. PGI activity and changes in carbohydrate composition suggests the existence of some control to fit the requirements of the intense carbon flow from starch to sucrose.
Cordenunsi
B R
BR
Department of Food Science and Experimental Nutrition, College of Pharmaceutical Sciences, University of São Paulo, SP, Brasil.
Oliveira do Nascimento
J R
JR
Vieira da Mota
R
R
Lajolo
F M
FM
D050260:Carbohydrate Metabolism; D002848:Chromatography, DEAE-Cellulose; D004591:Electrophoresis, Polyacrylamide Gel; D005956:Glucose-6-Phosphate Isomerase / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D007526:Isoelectric Point; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D028521:Musa / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
D007527:Isoenzymes; D013395:Sucrose; D005956:Glucose-6-Phosphate Isomerase