PMID: 7918467

 

    Legend: Sugar

Title : Structure of human apolipoprotein D : locations of the intermolecular and intramolecular disulfide links

Abstract :
  1. We have determined the primary structure of human apolipoprotein D ( apoD ) by aligning peptides derived from digestions by cyanogen bromide, trypsin, and chymotrypsin
  2. Our results confirm the primary structure derived from cDNA [Drayna et al. (1986) J. Biol
  3. Chem
  4. 261, 16535-16539]
  5. ApoD consists of 169 amino acid residues , including 5 cysteines
  6. Tryptic peptide analysis indicated that Cys41 and Cys16 are joined by a disulfide bridge
  7. Using a combination of manual Edman degradations and mass spectrometric analysis on a purified cluster of chymotryptic fragments , we identified an intramolecular disulfide bridge between Cys8 and Cys114 and an intermolecular bridge between Cys116 of apoD and Cys6 of apoA-II
  8. In addition, sites of N-glycosylation were found at Asn45 and Asn78
  9. Because apoD contains two intramolecular disulfide linkages and has a high content of proline to disrupt alpha-helical structures, formation of the amphipathic helical regions that characterize the other soluble apolipoproteins is unlikely
  10. We conclude that apoD binds to lipoprotein surfaces through structures other than alpha-helices, such as disulfide links