Schistosoma mansoni: Incorporation and metabolism of protein amino acids In vitro

Abstract

1. 1. The amino acid composition of total proteins in six stages of the life cycle of Schistosoma mansoni was determined by routine autoanalysis of acid hydrolysates. Aspartate, glutamate and glycine were consistently the most abundant protein amino acids in all stages. 2. 2. Incorporation of each of the protein amino acids into adult and egg proteins was determined using 72 hr cultures in complex media. Incorporation rates varied widely and there was no correlation between abundance in protein and the rate of incorporation. 3. 3. Only five amino acids were interconverted to other amino acids which were themselves incorporated into worm and egg proteins (ala, arg, asp, gly, ser); of these only two (glu from ala and pro from arg) appeared to be of quantitative significance. Exogenous glucose yielded only three protein amino acids (ala, asp, glu). 4. 4. The data are considered in the light of differences in egg and adult protein synthesis and with particular regard to potential chemotherapy at this level.