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.The female jojoba shrub (Simmondsia chinensis [Link] Schneider) produces numerous seeds which contain about half of their fresh weight as a unique liquid wax (13). Primarily because of the economic value of this liquid wax, the native Sonoran Desert plant is the subject of intense study to improve productivity in cultivation (13,34 Aminopeptidase and Carboxypeptidase) in Germinating Jojoba Cotyledons. Uniform seedlings were harvested at 3-day intervals; the cotyledons were removed and chopped with a razor blade. The minced cotyledons were homogenized with a Polytron Homogenizer (speed setting 8) for 1 min in 8.0 ml/g fresh weight 25 mm citrate-phosphate buffer containing 5.0 mm ME (pH 7.2). The homogenate was filtered through Miracloth and centrifuged at 10,000g for 10 min. The resulting supernatant was used directly for endopeptidase and aminopeptidase assays. For carboxypeptidase assays, the supernatant was dialyzed overnight against the above buffer. All preceding steps were carried out at 0 to 5°C. Duplicate assays for each enzyme were conducted on two separate extractions. Results were reproducible.Endopeptidase Assay. EPA was assayed with Azocoll (Calbiochem) as the substrate. Reaction mixtures contained 2.0 ml extract and 5.0 mg Azocoll in 2.0 ml 0.1 M citrate-phosphate buffer containing 5.0 mM ME. Assays were conducted at pH 4, 5, 6, 7, and 8 as determined at the beginning and end of each assay. The reaction was incubated at 45°C for 2 h with vigorous shaking (about 250 rpm). The reaction was terminated by removing the undigested substrate through centrifugation (7) followed by the addition of an equal volume of 4.0%o ...