Activities of glycosidases during fruit development and ripening of tomato (Lycopersicum esculantum L.): implication in fruit ripening

Jagadeesh, B. H. and Prabha, T. N. and Srinivasan, K. (2004) Activities of glycosidases during fruit development and ripening of tomato (Lycopersicum esculantum L.): implication in fruit ripening. Plant Science, 166. pp. 1451-1459.

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Abstract

Glycosidases such as beta-hexosaminidase, alpha-mannosidase and alpha-galactosidase are believed to play a major role in textural softening during fruit ripening. The activities of beta-hexosaminidase and alpha-galactosidase, which were low initially during fruit development, significantly increased during ripening in tomato.Onthe other hand, activity of alpha-mannosidase, which increased during fruit development, steadily increased further during ripening after a transient decrease. The specific activity of beta-hexosaminidase and alpha-mannosidase in tomato extracts considerably decreased upon dialysis. Protein profiles on SDS-PAGE showed differences in the presence of protein bands between fruit developmental and ripening stages. The carbohydrate/protein ratio increased from fruit developmental to ripening stage with a highest value at the climacteric stage, suggesting active synthesis of glycoproteins. All the three alpha-mannosidase isoforms in tomato were found to have a common subunit having a molecular mass of 55 kDa, while isoform-II and -III were found to have an additional subunit of molecular mass 36 kDa. Antibody raised against bell capsicum alpha-mannosidase also cross-reacted with tomato alpha-mannosidase. The intensity of cross-reaction increased towards ripening stage of the fruit from developmental stage, showing ripening specificity of this enzyme in tomato fruits. Immuno-diffusion study with tomato tissue blotting also supported this inference.

Item Type:	Article
Uncontrolled Keywords:	beta-Hexosaminidase; alpha-Mannosidase; beta-Galactosidase; Fruit ripening; Tomato
Subjects:	600 Technology > 08 Food technology > 23 Vegetables > 03 Tomato
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	25 Sep 2007 12:06
Last Modified:	01 Jun 2012 11:18
URI:	http://ir.cftri.res.in/id/eprint/1441

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