Poly-L-proline (PLP) takes two extreme local conformations, right-handed helix (Helix-I) and left-handed helix (Helix-II) and two overall conformations at a steady-state, PLP-I and -II, each of which is constructed by sequences of Helix-I and -II, respectively. The study with IR and proton NMR spectroscopy has verified that PLP-I dissolved in glacial acetic acid is gradually converted into PLP-II (forward-mutarotation) and PLP-II dissolved in a mixture of glacial acetic acid and n-propanol is gradually converted into PLP-I (reverse-mutarotation), and has roughly evaluated the rate of the conformational change: It takes ca. 48 hrs. and ca. 40∼50 hrs. at 25°C, respectively, for the forward- and reverse-mutarotation process to reach the middle stage. The analysis of the SAXS data has shown that the conformation of PLP at the middle stage of the forward mutarotation process is represented by joining alternatively rodlike structure of Helix-I and -II, which has equal 180 $\pm$ 90 proline residues per a helical rod, whereas the overall conformation of PLP-II dissolved in CD₃COOD is represented by an intact helical rod or an interrupted helical rod having a few breaking-points. These data suggest that the conformational transition of PLP would proceed in a zipper-like pattern.

Poly-L-脯氨酸（PLP）具有两个极端的局部构象，即右手螺旋（Helix-I）和左手螺旋（Helix-II），以及处于稳态的两个整体构象PLP-1和-II，每个分别由螺旋-I和-II的序列构建。红外和质子NMR光谱的研究证实，溶解在冰醋酸中的PLP-I逐渐转化为PLP-II（正变位），溶解在冰醋酸和正丙醇的混合物中的PLP-II逐渐转化成PLP-I（反向变旋），并已大致评价了构象的变化率：这需要约 48小时 和。40〜50小时 分别在25°C的温度下进行正变变和中间变变。对SAXS数据的分析表明，在正向旋转过程的中间阶段，PLP的构象由Helix-I和-II的交替杆状结构连接而成，其结构等于180$\pm$每个螺旋杆有90个脯氨酸残基，而溶解在CD ₃ COOD中的PLP-II的总体构象由完整的螺旋杆或具有几个断裂点的间断螺旋杆表示。这些数据表明，PLP的构象转变将以拉链状模式进行。