Localisation of the major reactive lysine residue involved in the selfcrosslinking of proteinase‐activated Limulus α 2‐macroglobulin

FEBS Letters

Armstrong, Peter B.¹  Husted, Lise B.²  Sottrup-Jensen, Lars²  Dolmer, Klavs² 

[1] Marine Biological Laboratory, Woods Hole, MA 02543, USA;Department of Molecular and Structural Biology, C.F. Møllers Allé bldg. 130, University of Aarhus, DK-8000 Århus C, Denmark

关键词: α 2-Macroglobulin superfamily;    Proteinase inhibitor;    Thiol ester;    Crosslink;    Limulus;    α2M;    α2-macroglobulin;    α2MR/LRP;    α2M-receptor/LDL-receptor related protein;    CMCys;    S-carboxymethylcysteine;    DCI;    3;    4-dichloroisocoumarin;    DTE;    dithioerythritol;    HPLC;    high-performance liquid chromatography;    LDL;    low density lipoprotein;    PTH;    phenylthiohydantion;    RP;    reverse phase;    TFA;    trifluoroacetic acid;   

DOI  :  10.1016/0014-5793(96)00852-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

When α ₂-macroglobulin (α ₂M) from the American horseshoe crab, Limulus polyphemus, reacts with proteinases, its thiol esters, like those of other α-macroglobulins, become activated, leading to the formation of covalently crosslinked species that can be detected as high molecular weight bands in reducing SDS-PAGE. While other α-macroglobulins extensively form crosslinks to the reacting proteinase, Limulus α ₂M does not. It rather becomes internally crosslinked. It was found from N-terminal sequence analysis of purified [¹⁴C]carboxymethylated peptides from Limulus α ₂M-trypsin complexes that an isopeptide bond formed in approx. 60% yield from the thiol esterified Gln-1002 specifically to Lys-254 in the opposing monomer of the disulphide bridged dimer is the main cause of the internal crosslinking.

【 授权许可】

Unknown