biologia plantarum

Biologia plantarum 23:133-140, 1981 | DOI: 10.1007/BF02878420

Proteolytic activities in seeds ofVigna unguiculata (L.) Walp

Iracema L. Ainouz¹, Norma B. Benevides, Ana L. P. Feeitas

¹ Department of Biochemistry and Molecular Biology, Federal University of Ceara, Fortaleza, Brazil

Proteolytic activities were studied in cotyledons of germinated and mature dry seed and axis of mature dry seed ofVigna unguiculata (L.) Walp. cv. Seridó using the following substrates: hemoglobin (pH 3.5), casein (pH 6.0), LPA (pH 7.0), and BAPA (pH 7.6). During the germination period (six days) examined, the total activities of LPA-ase and BAPA-ase decreased progressively in cotyledons corresponding to protein depletion. Consequently, the specific activities of the above proteases remain practically constant. In the case of caseinase and hemoglobinase, total activities increased in the cotyledons up to the third day of germination. Thereafter there was a decrease in these activities (total) but an increase in specific activities. Higher values than in the cotyledons for all the activities were obtained with the axis of mature dry seed. A 25 to 50 % ammonium sulfate fraction of a buffered extract from mature dry seed was used as source of enzyme for all the substrates used. Sephadex G-100 chromatography of the 25 to 50 % (NH⁴)²SO⁴ fraction gave two main peaks which correspond to relative molecular mass of 100 000 and 60 000 and contained all the activities.

Received: July 1, 1980; Accepted: July 17, 1980; Published: March 1, 1981  Show citation