Introduction of a low molecular weight agonist peptide for complement C3a receptor into soybean proglycinin A(1a)B(1b) subunit by site-directed mutagenesis

LPLPR, a complement C3a agonist peptide, with hypocholesterolemic activity was introduced into the homologous site of soybean proglycinin A(1a)B(1b) s ubunit by site-directed mutagenesis, This modified proglycinin was expresse d in E, coli and recovered from the insoluble fraction. LPLPR was released by the action of chymotrypsin and trypsin as expected. Furthermore, two pep tides (RPSYLPLPR and PSYLPLPR) with extended sequence at the amino-terminus of LPLPR were obtained. Their ileum-contracting activity was 9 similar to 13 times stronger than that of LPLPR, The overall yields of purified LPLPR, RPSYLPLPR and PSYLPLPR were 25%, 12%, and 0.7% respectively.