趨化激素(chemokine)具有吸引白血球的能力以及抑制或是促進血管新生的功能，而它具有什麼功能和他的聚合狀態有關(oligomerization state)。CXCL4(又稱作第四型血小板因子， CXCL4)是第一個被發現具有抑制血管新生的區劃激素。在過去的研究中指出，四聚體的CXCL4 和黏多醣(GAGs)具有很強的結合能力，而單體的CXCL4 就具備和受體結合的能力並進行其下游的反應。趨化激素能以不同型態的多聚體來執行不同的的生理活性，為了精準地調控下游所引發的反應，研究它如何形成聚合狀態是勢在必行的工作。然而在過去有關於趨化激素聚合狀態的研究，大部分都會在聚體接合界面的胺基酸做點突變來做進一步的研究。在過去的研究中可以發現，然而有趣的是，加入還原性試劑二硫蘇糖醇(DTT)能夠將雙硫鍵打斷之外，也能夠改變CXCL4 聚和狀態，使不對稱的四聚體成為對稱的二聚體，這是個嶄新的方式來調控聚體狀態，因此我們決定以加入還原性試劑(DTT)的方式來研究影響聚體形成的重要因素。為了找出由DTT 還原過後的CXCL4 是屬於哪一種的二聚體，我們首先確認還原態下CXCL4 的分子量，接著測量胺基酸骨架和水交換的程度以及R1、R2、NOE 的動態研究。在以上的研究中我們發現到N 端的胺基酸有著不尋常的保護，使其不容易和水接觸，並且和其他趨化激素有著截然不同的動態研究結果。因此我們推測被DTT 還原的CXCL4 比較像CC 型態的雙體，在未來我們會從結構的觀點來證明這個推測。

Chemokines were described for their ability to recruit leukocytes and affect inflammatory. The functions have been controlled by their oligomerization states. CXCL4 (also named platelet factor 4, PF4) is the first chemokine identified with anti-angiogenesis function. Tetrameric CXCL4 has high affinity to Glycosaminoglycans (GAGs) while monomeric CXCL4 has be speculated to bind its protein receptor to trigger the downstream signal. For precisely executing the biological function, certain chemokine oligomers exist under different conditions. To control chemokine oligomerization relies on point mutations on residues at the oligomer interface. Interestingly, removal of disulfide linkages of CXCL4 modulates the oligomerization state from asymmetric tetramer to symmetric dimer. The factor is novel in controlling chemokine oligomers. To figure out the mechanism and dimer type, we checked molecular size, backbone solvent accessibility, and molecular dynamics based on R1, R2 and NOE measurements. We demonstrate that the N-terminal region is with great protection from solvent. We also reveal special dynamics in the N-terminal region. This result is different than other folded chemokines. We speculate that DTT-reduced CXCL4 more likely adopts CC-type dimer fold. To directly answer the question, structural determination will be required in the future.

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