scholarly journals Seasonal Fluctuations of Some Enzymes Relating to Sucrose and Sorbitol Metabolism in Peach Fruit

1990 ◽  
Vol 115 (2) ◽  
pp. 278-281 ◽  
Author(s):  
Takaya Moriguchi ◽  
Tetsuro Sanada ◽  
Shohei Yamaki
Keyword(s):  
Sucrose Synthase ◽  
Prunus Persica ◽  
Early Stage ◽  
Sucrose Phosphate Synthase ◽  
Acid Invertase ◽  
Peach Fruit ◽  
Development Activity ◽  
Stage Of Development ◽  
Sugar Levels ◽  
Sucrose Phosphate

Sugar levels and composition were determined in developing `Hakuto' peach (Prunus persica Batsch var. vulgaris Maxim.) fruit. Glucose and fructose in nearly equal amounts were the predominant sugars detected during the early stage of development. Sucrose subsequently began to accumulate and was the predominant sugar in mature fruit. Sorbitol remained at a low level throughout development. The large increase in the amount of sucrose was accompanied by a rapid increase in sucrose synthase (EC 2.4.1.13) activity. Sucrose phosphate synthase (EC 2.4.1.14) was also detected in flesh extracts, but the activities were low throughout development. Acid invertase (EC 3.2.1.26) activity was highest in young fruit and declined with development. Activity, however, increased again at a later stage of development. Peach fruit contained appreciable sorbitol oxidase activity, while other sorbitol-related enzymes were barely detectable, suggesting that transported sorbitol was predominantly converted to glucose. These results suggest that the supply of glucose and fructose depends on acid invertase and sorbitol oxidase, and that accumulation of sucrose depends on-sucrose synthase.

scholarly journals Levels and Role of Sucrose Synthase, Sucrose-phosphate Synthase, and Acid Invertase in Sucrose Accumulation in Fruit of Asian Pear

1992 ◽  
Vol 117 (2) ◽  
pp. 274-278 ◽  
Author(s):  
Takaya Moriguchi ◽  
Kazuyuki Abe ◽  
Tetsuro Sanada ◽  
Shohei Yamaki
Keyword(s):  
Sucrose Synthase ◽  
Sucrose Phosphate Synthase ◽  
Invertase Activity ◽  
Acid Invertase ◽  
Sucrose Accumulation ◽  
Sucrose Content ◽  
Soluble Acid Invertase ◽  
Asian Pear ◽  
Soluble Acid ◽  
Sucrose Phosphate

Soluble sugar content and activities of the sucrose-metabolizing enzymes sucrose synthase (SS) (EC 2.4.1.13), sucrose-phosphate synthase (SPS) (EC 2.4.1.14), and acid invertase (EC 2.4.1.26) were analyzed in the pericarp of fruit from pear cultivars that differed in their potential to accumulate sucrose to identify key enzymes involved in sucrose accumulation in Asian pears. The Japanese pear `Chojuro' [Pyrus pyrifolia (Burro. f.) Nakai] was characterized as a high-sucrose-accumulating type based on the analysis of mature fruit, while the Chinese pear `Yali' (P. bretschneideri Rehd.) was a low-sucrose-accumulating type throughout all developmental stages. The activity of SS and SPS in `Chojuro' increased during maturation concomitant with sucrose accumulation, whereas the activity of these enzymes in `Yali' did not increase during maturation. The activity of SS and SPS in the former were seven and four times, respectively, higher than those in the latter at the mature stage. Further, among 23 pear cultivars, SS activity was closely correlated with sucrose content, while SPS activity was weakly correlated. Soluble acid invertase activity in `Chojuro' and `Yali' decreased with fruit maturation, but the relationships between soluble invertase activity and sucrose content were not significant. The results indicate that SS and SPS are important determinants of sucrose accumulation in Asian pear fruit and that a decrease of soluble acid invertase activity is not absolutely required for sucrose accumulation.

scholarly journals Sucrose Metabolism and Purification and Characterization of Sucrose Synthase from Lycopersicon esculentum var. cerasiforme Fruit

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 491E-491
Author(s):  
Md. Shahidul Islam ◽  
S. Khan ◽  
T. Matsui
Keyword(s):  
Lycopersicon Esculentum ◽  
Sucrose Synthase ◽  
Enzymatic Reaction ◽  
Sucrose Phosphate Synthase ◽  
Acid Invertase ◽  
Sucrose Metabolism ◽  
Cherry Tomato ◽  
Fructose 2 ◽  
Sucrose Phosphate ◽  
Phosphate Synthase

Sucrose metabolism was followed in developing fruit of domesticated cherry tomato (Lycopersicon esculentum var. cerasiforme Alef.). The high amounts of reducing sugars were consistently linked to high soluble acid invertase (EC 3.2.1.26), whereas sucrose synthase (EC 2.4.1.13) followed the same pattern of sucrose levels and reached a peak of activity during early stage of maturation and then decreased to near nil. In comparison, sucrose phosphate synthase (EC 2.4.1.14) activity remain relatively constant throughout development. Thus, sucrose synthase and acid invertase, rather than sucrose phosphate synthase, are the critical enzymes regulating sucrose accumulation in tomatoes. Cultivated cherry tomato sucrose synthase (UDP-glucose: D-fructose 2-glucosyltransferase) was purified to homogeneity by ammonium sulfate precipitation, anion exchange chromatography on DEAE-Toyopreal 650, and gel filtration on Sephadex G-200. Further purification to homogeneity resulted from a single band from SDS-PAGE. The enzyme was identified as a homotetramer with a total molecular mass of 370 kDa and subunits of 92 kDa. The enzyme showed maximum activity for the cleavage and synthesis of sucrose was at pH 7.0 and 8.0, respectively, and the optimum temperature was 40°C in both directions for HEPES-KOH buffer. The enzymatic reaction followed typical Michaelis–Menten kinetics, with the following parameters: Km (fructose),7.4; Km (UDP-glucose), 0.2612; Km (sucrose), 33.24; Km (UDP), 0.0946. The enzyme was very sensitive to inhibition by heavy metals.

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