title: A mechanism-based probe for gp120-Hydrolyzing antibodies.
abstract: An antigenic peptide analogue consisting of HIV gp120 residues 421-431 (an antigen recognition site probe) with diphenyl amino(4-amidinophenyl)methanephosphonate located at the C-terminus (a catalytic site probe) was synthesized and its trypsin and antibody reactivity characteristics were studied. Antibodies to the peptide determinant recognized the peptidyl phosphonate probe. Trypsin was inhibited equipotently by the peptidyl phosphonate and its simple phosphonate counterpart devoid of the peptide determinant. The peptidyl phosphonate inhibited the gp120-hydrolyzing activity of a catalytic antibody light chain. It was bound covalently by the light chain and the binding was inhibited by the classical active-site directed inhibitor of serine proteinase, diisopropyl fluorophosphate. These results reveal that the peptidyl phosphonate ester can serve as a probe for the antigen recognition and catalytic subsites of proteolytic antibodies.
authors.affiliation: Chemical Immunology and Therapeutics Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, 6431 Fannin, Houston, TX 77030, USA.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Taguchi
authors.forename: Gary
authors.initials: G
authors.lastname: Burr
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Karle
authors.forename: Stephanie
authors.initials: S
authors.lastname: Planque
authors.forename: Yong-Xin
authors.initials: YX
authors.lastname: Zhou
authors.forename: Sudhir
authors.initials: S
authors.lastname: Paul
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nishiyama
mesh_terms: D000818:Animals; D000906:Antibodies / Q000737:chemistry*; D002384:Catalysis; D015195:Drug Design; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000276:immunology*; D006868:Hydrolysis; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D063065:Organophosphonates; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000737:chemistry; D014357:Trypsin / Q000737:chemistry
chemical_list: D000906:Antibodies; D015699:HIV Envelope Protein gp120; D063065:Organophosphonates; D010455:Peptides; D015842:Serine Proteinase Inhibitors; D012710:Serum Albumin, Bovine; D010450:Endopeptidases; D014357:Trypsin