Interaction of the octapeptide angiotensin II with a high-affinity single-chain Fv and with peptides derived from the antibody paratope

The amino-acid sequence of the very high-affinity anti-angiotensin II monoc lonal antibody 4D8 was predicted from the nucleotide sequence of the heavy and light chain variable genes. The single-chain variable fragment (scFv) w as constructed and expressed in Escherichia coli as a soluble protein and a t the surface of the filamentous M13 phage and was compared with the full-l ength antibody (Ab). The scFv showed the same specificity profile and affin ity constant as the intact antibody (5.0 X 10(10) and 8.0 x 10(10) M-1. res pectively, by Scatchard analysis). Several peptides from the set of overlap ping dodecapeptides covering the variable domains of 4D8 mAb were found to specifically bind biotinylated angiotensin II: peptides from the L1, L2. L3 and H1 regions had the strongest capacity to bind the antigen. (C) 2001 El sevier Science B.V. All rights reserved.