Short-lived complexes between myelin basic protein peptides and IAk.
Kinetic rate constants and the equilibrium dissociation constant have been determined for the reaction between an affinity-purified class II major histocompatibility complex molecule IAk and a myelin basic protein analogue peptide, fluorescein-labeled Ac(1-14)A4C15. Under the experimental conditions used, the lifetime of the peptide-free IAk molecule with respect to inactivation is 3.1 hr. The equilibrium dissociation constant, 3.3 +/- 1.7 microM, is determined from measurements of the kinetics of peptide inhibition of IAk inactivation. The measured peptide dissociation halftime is relatively short, 30 min, and the deduced association rate is 100 M-1.s-1. The rate constants and the equilibrium constant are similar to those characteristic of kinetic intermediates in reactions of peptides and class II proteins that lead to long-lived terminal complexes.
Mason
K
K
Department of Chemistry, Stanford University, CA 94305.
McConnell
H M
HM
D000595:Amino Acid Sequence; D000818:Animals; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000737:chemistry / Q000276:immunology*; D010455:Peptides / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding
D000949:Histocompatibility Antigens Class II; D004676:Myelin Basic Protein; D010455:Peptides