Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran.
Phytochemistry. 2013 Mar;87:16-22. doi: 10.1016/j.phytochem.2012.12.006. Epub 2013 Jan 10.
Ficin (EC 3.4.22.3), a cysteine endoproteolytic protease in fig trees' latex, has multiple isoforms. Until now, no data on autolysis of individual ficins (ficin isoforms) are available. Following purification, ficins' autolysis was determined by HPLC chromatogram changes and ultrafiltrations at different temperatures and storage times. These results showed that the number of HPLC peaks in latex proteins purification of Ficus carica cv. Sabz varied from previous fig varieties or cultivars. Proteolytic activity of ficins was inhibited by specific cysteine protease inhibitors, confirming the participation of the cysteine residue in the active site. The zeta potential of the first two eluted peaks (I and II) was negative, while that of other peaks were positive. All ficins were susceptible to autolysis when stored at high temperatures. In contrast, only the last two ficins (B, C) were prone to autolysis at cold temperature after long storage period. The rate of degradation of the ficins was significantly increased with the increased storage time. The ficin (A) related to peak (III) had the highest and the lowest surface hydrophobic patches and ratio of autolytic to proteolytic activity, respectively.
无花果乳清中的半胱氨酸内肽酶 Ficin（EC 3.4.22.3）具有多种同工酶。到目前为止，尚无关于各个 Ficin（Ficin 同工酶）自解的数据。在纯化后，通过 HPLC 色谱图变化和不同温度和储存时间的超滤来确定 Ficin 的自解。这些结果表明，Ficus carica cv. Sabz 乳清蛋白纯化的 HPLC 峰数量与以前的无花果品种或品种不同。Ficin 的蛋白水解活性被特定的半胱氨酸蛋白酶抑制剂抑制，证实了半胱氨酸残基在活性部位的参与。前两个洗脱峰（I 和 II）的 ζ 电位为负，而其他峰的 ζ 电位为正。所有 Ficin 在高温下储存时都容易自解。相比之下，只有最后两个 Ficin（B、C）在长时间储存后在低温下容易自解。Ficin 的降解速度随储存时间的增加而显著增加。与峰（III）相关的 Ficin（A）具有最高和最低的表面疏水性斑和自解与蛋白水解活性的比值。
