Fig. 1: Fab15H6.v4 inhibits the enzymatic activity of HTRA1^FL and HTRA1^PD through an allosteric mechanism.

a HTRA1^FL domain architecture. Enzyme activity of HTRA1^FL, HTRA1^PD, and catalytically inactive HTRA1^PD/SA in the presence of Fab15H6.v4. Control Fab33 (anti-PCSK9) does not affect enzymatic activity. b Cleavage of macromolecular substrates Dickkopf-related protein 3 (DKK3), BIGLYCAN, and DECORIN by HTRA1^FL (51 kDa) and HTRA1^PD (24 kDa) in the presence of Fab15H6.v4. Right panel: cleavage assay control with individual proteins. Asterisks (*) indicate the contaminant of the control Fab33 preparation. c Labeling of HTRA1^FL, HTRA1^PD, and HTRA1^PD/SA active site using a small fluorescent activity-based probe (TAMRA-ABP) in the presence of Fab15H6.v4. HTRA1^FL undergoes self-cleavage and therefore appears as two bands in the TAMRA-ABP assay. d Size-exclusion profiles of HTRA1^PD/SA:Fab15H6.v4 (red, calc. mass = 228 kDa) and full length HTRA1^FL/SA:Fab15H6.v4 (blue, calc. mass = 311 kDa) complexes. Protein standards for estimated size comparison are in grey. e Kinetics of Fab15H6.v4 binding to HTRA1^PD and to HTRA1^PD pre-incubated with 7-mer ABP determined by Surface Plasmon Resonance (SPR). Bar graphs in (a) and kinetic data in (e) are presented as the mean ± S.D. of three independent experiments. Images in (b, c), as well as chromatogram in (d) are representative of two independent experiments. Source data are provided as a Source Data file.