Goossens Koen, Haelewyn Joost, Meersman Filip, De Ley Marc, Heremans Karel
Laboratorium voor Chemische en Biologische Dynamica, Celestijnenlaan 200 D, B-3001 Leuven, Belgium.
Biochem J. 2003 Mar 1;370(Pt 2):529-35. doi: 10.1042/BJ20020717.
The effect of hydrostatic pressure on the secondary structure of recombinant human interferon-gamma (rhIFN-gamma) and its biologically inactive truncated form rhIFN-Delta C15 has been studied using Fourier-transform IR (FTIR) spectroscopy. In situ observation of the pressure-induced changes using the diamond anvil cell shows that the alpha-helical structure is mainly transformed into disordered structure at high pressure. Increasing pressure also induces the formation of a gel. Addition of 0.5 M MgCl(2) significantly reduces the pressure stability. Releasing the pressure below 300 MPa results in the formation of intermolecular antiparallel beta-sheets, which is seldom observed. This suggests that the intermolecular beta-sheet of rhIFN-gamma is stabilized by electrostatic interactions that are disrupted at high pressure. For comparison we also studied the effect of temperature. Temperature-induced changes reflect extensive transformation of alpha-helical structure into intermolecular antiparallel beta-sheet, as is usually observed for most proteins.
利用傅里叶变换红外（FTIR）光谱研究了静水压力对重组人干扰素-γ（rhIFN-γ）及其无生物活性的截短形式rhIFN-ΔC15二级结构的影响。使用金刚石对顶砧池对压力诱导的变化进行原位观察表明，在高压下α-螺旋结构主要转变为无序结构。压力增加还会诱导凝胶的形成。添加0.5 M MgCl₂会显著降低压力稳定性。在300 MPa以下释放压力会导致分子间反平行β-折叠的形成，这种情况很少见。这表明rhIFN-γ的分子间β-折叠通过高压下被破坏的静电相互作用得以稳定。为作比较，我们还研究了温度的影响。温度诱导的变化反映出α-螺旋结构广泛转变为分子间反平行β-折叠，这是大多数蛋白质通常会出现的情况。
