Significance of the pH-induced conformational changes in the structure of C-reactive protein measured by dual polarization interferometry.
Emerging evidence indicates that the conformation of C-reactive protein (CRP) plays important roles in human inflammation and cardiovascular disease (CVD). The different conformations in the structure of CRP under different pH conditions remain an important issue to be investigated for explaining various functions of CRP under certain physiologic and pathologic conditions. We directly measured the pH-induced conformational changes in the structure of CRP by dual polarization interferometry (DPI). The CRP was attached to an aldehyde-functionalized DPI sensor chip at a concentration of 50 μg/ml, and attained 2.019 ng/mm2 to form a surface coverage with a 1.71×10(-14) mol/mm2 CRP monolayer. A pentagonal structure with an average monolayer thickness value of 5.70±0.12nm and a layer density of 0.374±0.058 g/cm2 was obtained at pH 7.0. Moreover, the DPI biosensor signals directly reflected the considerable structural parameters and phenomena of conformational changes of CRP in a pH range of 2.0-10.0. The results obtained showed that the pentameric structure of CRP might dissociated into monomers or monomer aggregates as the pH shifts toward both acidic and alkaline conditions, but only partial rearrangements of CRP subunits might occur at extremely acidic physiological conditions. Considering the proinflammatory effect and subclinical chronic inflammation, pH-induced conformational changes in the structure of CRP between monomeric and pentameric formations may strongly relate to vascular atherosclerosis and subsequent CVD.
Sheu
Bor-Ching
BC
Department of Obstetrics and Gynecology, College of Medicine and the Hospital, National Taiwan University, Taipei, Taiwan. bcsheu@ntu.edu.tw
Lin
Yun-Han
YH
Lin
Chih-Chen
CC
Lee
Adam Shih-Yuan
AS
Chang
Wen-Chun
WC
Wu
Jung-Hsin
JH
Tsai
Jui-Chang
JC
Lin
Shiming
S
D002097:C-Reactive Protein / Q000737:chemistry* / Q000648:ultrastructure*; D006863:Hydrogen-Ion Concentration; D007368:Interferometry / Q000379:methods*; D011487:Protein Conformation; D011489:Protein Denaturation; D012031:Refractometry / Q000379:methods*
D002097:C-Reactive Protein