Abstract
Digestion of methylamine-treated α 2-macroglobulin (α 2M·MA) with catalytic amounts of papain at pH 4.5 has been investigated. Cleavage of Lys(1313)-Glu resulted in two major products, which could be separated by gel chromatograhy: a large disulfide bridged fragment set nearly the size of intact α 2M·MA, and an 18 kDa fragment, constituting the carboxy-terminal domain of α 2M. This domain contained the receptor recognition site, exposed as a result of cleavage of the internal β-cysteinyl-γ-glutamyl thiol esters in α 2M. Compared with α 2M-trypsin complex the apparent affinity for binding to rat hepatocyte receptors was 0.1 and 2% at 4 and 37°C, respectively. The receptor-binding domain presumably forms a compact globular β-barrel-type structure, stable at pH 2.5–9.0. Chemical modification experiments suggest that receptor binding is contributed by a determinant formed by the precise folding of the polypeptide chain.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
