A Serum Amyloid a Peptide Contains a Low-Ph Heparin Binding Site which Promotes AA-Amyloidogenesis in Cell Culture

2004 ◽  
pp. 194-196
Author(s):  
Robert Kisilevsky ◽  
John Ancsin ◽  
Elena Elimova
Keyword(s):  
Cell Culture ◽  
Binding Site ◽  
Serum Amyloid A ◽  
Low Ph ◽  
Serum Amyloid ◽  
Heparin Binding ◽  
Amyloid A ◽  
Heparin Binding Site

Abstract 110: The Separation of Serum Amyloid A from HDL is Mediated by Heparan Sulfate Through Histidine Dependent Interactions: HDL Function is Enhanced but Amyloid-Fibrils may be the “Price to Pay”¼

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
John B Ancsin ◽  
Kim Munro ◽  
Shui-Pang Tam ◽  
Michael H Davidson
Keyword(s):  
Heparan Sulfate ◽  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
3D Structure ◽  
Serum Amyloid ◽  
Acidic Ph ◽  
Heparin Binding ◽  
Additional Time ◽  
Amyloid A ◽  
Hdl Function

Serum amyloid A (SAA) is an acute-phase protein that circulates bound to high density lipoprotein (HDL) and can influence HDL function as part of a poorly understood defense re-sponse to tissue trauma or infection. We have previously demonstrated that under mildly acidic pH the glycosaminoglycans, heparan sulfate (HS) and heparin can interact with HDL-SAA and cause SAA to dissociate from HDL. This remodeling improves HDL functionality but also predisposes SAA to form AA-amyloid fibrils. In this study we explore some potential pathophysiological conditions in vitro that could influence this HS/HDL-SAA remodeling process and the fate of SAA in vivo. SAA’s binding affinity for heparin was found to be enhanced by acidic pH and low concentrations of urea. The heparin dependent remodeling of HDL-SAA was promoted by the partial denaturation of HDL-SAA. Moreover, HDL-SAA remodeling was observed to follow a strict SAA:heparin stoichiometry and could be partially inhibited with a short heparin oligosaccharide of 8-sugar units. Evidence is also presented that once dissociated from HDL, SAA requires additional time to organize into Triton x-100 resistant amyloid-like structures. Circular dichroism spectroscopic analysis and in silico modeling of SAA’s ionizable residues highlights the importance of the histidine-36 within a highly conserved, pH-sensitive HS-binding site (HSBS-pH). A peptide containing the HSBS-pH sequence was demonstrated to have AA-amyloid seeding activity in a cell culture system. The recent determination of the 3D structure for human SAA1.1 has allowed the opportunity to re-assess and validate the HS/heparin binding sequences that had previously been identified biochemically with short synthetic peptides. We postulate that the dissociation of SAA from HDL takes place during the retro-endocytosis of HDL-SAA and is an important aspect of SAA function not previously appreciated.

Prediction and experimental validation of a putative non-consensus binding site for transcription factor STAT3 in serum amyloid A gene promoter

2013 ◽  
Vol 1830 (6) ◽  
pp. 3650-3655 ◽  
Author(s):  
Prabha Tiwari ◽  
Lokesh P. Tripathi ◽  
Teppei Nishikawa-Matsumura ◽  
Shandar Ahmad ◽  
Soken-Nakazawa J. Song ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Experimental Validation ◽  
Serum Amyloid A ◽  
Gene Promoter ◽  
Serum Amyloid ◽  
Consensus Binding Site ◽  
Amyloid A

scholarly journals The Heparin/Heparan Sulfate-binding Site on Apo-serum Amyloid A

1999 ◽  
Vol 274 (11) ◽  
pp. 7172-7181 ◽  
Author(s):  
John B. Ancsin ◽  
Robert Kisilevsky
Keyword(s):  
Heparan Sulfate ◽  
Binding Site ◽  
Serum Amyloid A ◽  
Serum Amyloid ◽  
Amyloid A

Antithrombin-mediated Inhibition of Factor Vlla-Tissue Factor Complex by the Synthetic Pentasaccharide Representing the Heparin Binding Site to Antithrombin

1996 ◽  
Vol 76 (01) ◽  
pp. 005-008 ◽  
Author(s):  
Jean Claude Lormeau ◽  
Jean Pascal Herault ◽  
Jean Marc Herbert
Keyword(s):  
Binding Site ◽  
Tissue Factor ◽  
Residual Activity ◽  
Coagulation Factors ◽  
Heparin Binding ◽  
Experimental Conditions ◽  
First Order ◽  
Heparin Binding Site ◽  
Coagulant Activity

SummaryWe examined the effect of the synthetic pentasaccharide representing the minimal binding site of heparin to antithrombin on the antithrombin-mediated inactivation of factor Vila bound to tissue factor. This effect was compared to the effect of unfractionated heparin. Using purified recombinant human coagulation factors and either a clotting or an amidolytic assay for the determination of the residual activity of factor Vila, we showed that the pentasaccharide was an efficient antithrombin-dependent inhibitor of the coagulant activity of tissue factor-factor Vila complex. In our experimental conditions, assuming a mean MW of 14,000 for heparin, the molar pseudo-first order rate constants for ATIII-mediated FVIIa inhibition by ATIII-binding heparin and by the synthetic pentasaccharide were found to be similar with respective values of 104,000 ± 10,500 min-1 and 112,000 ± 12,000 min-1 (mean ± s.e.m., n = 3)

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