This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lin, Y.-H. Articles by Huang, A. H. C. Search for Related Content PubMed PubMed Citation Articles by Lin, Y.-H. Articles by Huang, A. H. C. Agricola Articles by Lin, Y.-H. Articles by Huang, A. H. C.

Articles

Involvement of Glyoxysomal Lipase in the Hydrolysis of Storage Triacylglycerols in the Cotyledons of Soybean Seedlings ¹

Biology Department, University of South Carolina, Columbia, South Carolina 29208

The total cotyledon extract of soybean (Glycine max [L.] Merr. var. Coker 136) seedlings underwent lipolysis as measured by the release of fatty acids. The highest lipolytic activity occurred at pH 9. This lipolytic activity was absent in the dry seeds and increased after germination concomitant with the decrease in total lipids. Using spherosomes (lipid bodies) isolated from the cotyledons during the peak stage of lipolysis (5-7 days) as substrates, about 40% of the lipase activity was found in the glyoxysomes after organelle breakage had been accounted for; the remaining activity was distributed among other subcellular fractions but none was found in the spherosomal fraction. The glyoxysomal lipase had maximal activity at pH 9, and catalyzed the hydrolysis of tri-, di-, and monoacylglycerols of linoleic acid, the most abundant fatty acid in soybean. The spherosomes contained a neutral lipase that could hydrolyze monolinolein and N-methylindoxylmyristate, but not trilinolein. This spherosomal lipase activity dropped off rapidly during early seedling growth, preceding lipolysis. Spherosomes isolated from either dry or germinated seeds did not possess lipolytic activity, and spherosomes from germinated seeds but not from dry seeds could serve as substrates for the glyoxysomal lipase. It is concluded that the glyoxysomal lipase is the enzyme catalyzing the initial hydrolysis of storage triacylglycerols.

¹ Supported by National Science Foundation PCM 8021970

This article has been cited by other articles:

				F. He, F. Huang, K. A. Wilson, and A. Tan-Wilson Protein storage vacuole acidification as a control of storage protein mobilization in soybeans J. Exp. Bot., March 1, 2007; 58(5): 1059 - 1070. [Abstract] [Full Text] [PDF]

				H. R. Sadeghipour and S. C. Bhatla Differential Sensitivity of Oleosins to Proteolysis During Oil Body Mobilization in Sunflower Seedlings Plant Cell Physiol., October 15, 2002; 43(10): 1117 - 1126. [Abstract] [Full Text] [PDF]

				C. Wang, K. P.C. Croft, U. Järlfors, and D. F. Hildebrand Subcellular Localization Studies Indicate That Lipoxygenases 1 to 6 Are Not Involved in Lipid Mobilization during Soybean Germination Plant Physiology, May 1, 1999; 120(1): 227 - 236. [Abstract] [Full Text]