Plant Physiol. Drug Metab Dispos
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Plant Physiology 68:1339-1344 (1981)
© 1981 American Society of Plant Biologists

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Articles

Proteolytic and Trypsin Inhibitor Activity in Germinating Jojoba Seeds (Simmondsia chinensis) 1

Deborah Samac and Richard Storey

Department of Biology, The Colorado College, Colorado Springs, Colorado 80903

Changes in proteolytic activity (aminopeptidase, carboxypeptidase, endopeptidase) were followed during germination (imbibition through seedling development) in extracts from cotyledons of jojoba seeds (Simmondsia chinensis). After imbibition, the cotyledons contained high levels of sulfhydryl aminopeptidase activity (APA) but low levels of serine carboxypeptidase activity (CPA). CPA increased with germination through the apparent loss of a CPA inhibitor substance in the seed. Curves showing changes in endopeptidase activity (EPA) assayed at pH 4, 5, 6, 7, and 8 during germination were distinctly different. EPA at pH 4, 5, 6, and 7 showed characteristics of sulfhydryl enzymes while activity at pH 8 was probably due to a serine type enzyme. EPA at pH 6 was inhibited early in germination by one or more substances in the seed. Activities at pH 5 and later at pH 6 were the highest of all EPA throughout germination and increases in these activities were associated with a rapid loss of protein from the cotyledons of the developing seedling.

Jojoba cotyledonary extracts were found to inhibit the enzymic activity of trypsin, chymotrypsin, and pepsin but not the protease from Aspergillus saotoi. The heat-labile trypsin inhibitor substance(s) was found in commercially processed jojoba seed meal and the albumin fraction of seed proteins. Trypsin inhibitor activity decreased with germination.

1 Supported by grants from Research Corporation and The Colorado College Faculty Research Board.






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Copyright © 1981 by the American Society of Plant Biologists