Starch Transformation During Banana Ripening: I ? The Phosphorylase and Phosphatase Behavior in Musa Acuminata

Abstract

Starch levels as well as the phosphorylases and acid phosphatase activity during ripening of the banana fruit was investigated. The concentrations and sequence of appearance of sucrose, glucose and fructose were determined by use of specific enzymatic reactions. During the climacteric period, the phosphatase activity increased while phosphorylase activity, which initially increased before starch transformation began, thereafter decreased in a complex pattern. The starch was transformed into sucrose with later formation of glucose and fructose. Four bands of phosphorylase multiple forms, detected electrophoretically, did not change during ripening. One of them was able to synthesize a branched starch‐using amylose as a primer and glucose 1 ‐phosphate as the substrate. Banana slices were infiltrated with water or solutions of cycloheximide or actinomycin D. Inhibition of phosphatase‐induced activity was recorded only in the cycloheximide group. No change in phosphorylase activity was detected in any of these infiltrated groups. Sucrose production from starch was partially inhibited both by actinomycin D and cycloheximide. The aformentioned results were interpreted as indicating the previous presence of phosphorylase in the preclimacteric phase without new synthesis during ripening. The increase of activity of phosphatase was probably due to ribosomal synthesis rather than to nucleic acid synthesis.

The physical, chemical and functional characterization of starches from Andean tubers: oca (Oxalis tuberosa Molina), olluco (Ullucus tuberosus Caldas) and mashua (Tropaeolum tuberosum Ruiz & Pavón)

“…Total starch, analyzed by the method described by Areas and Lajolo (1981), and total carbohydrates were estimated by difference. The dietary fiber (DF) content was determined using the enzymaticgravimetric method (Prosky et al, 1992).…”

Activity and expression of banana starch phosphorylases during fruit development and ripening

“…Hydrolytic and phosphorolytic enzymes are involved in this process although it is not known which mechanism triggers the process of granule degradation (Areˆas and Lajolo 1981;Garcia and Lajolo 1988;MacRae et al 1992).…”

Role of Sucrose Phosphate Synthase in Sucrose Biosynthesis in Ripening Bananas and Its Relationship to the Respiratory Climacteric

“…Starch degradation in bananas appears to be mediated primarily by phosphorylase (1,29,36). Early studies with bananas (29,36) reported a substantial increase in phosphorylase activity associated with the starch to sugar conversion.…”

“…Early studies with bananas (29,36) reported a substantial increase in phosphorylase activity associated with the starch to sugar conversion. Enzyme extraction procedures in bananas have since improved (2), and it now appears that phosphorylase activity of unripe bananas is sufficient to account for the rapid loss of starch content during ripening (1). With regard to sucrose synthesis, Terra et al (33) reported an increase in sucrose synthase activity during ripening and suggested that sucrose synthase may play a major role in the regulation of sucrose accumulation.…”