Hamuro Yoshitomo, Coales Stephen J, Molnar Kathleen S, Tuske Steven J, Morrow Jeffrey A
ExSAR Corporation, 11 Deer Park Drive, Suite 103, Monmouth Junction, NJ 08852, USA.
Rapid Commun Mass Spectrom. 2008 Apr;22(7):1041-6. doi: 10.1002/rcm.3467.
Statistical analysis of data from 39 proteins (13 766 amino acid residues) digested with immobilized porcine pepsin under conditions compatible with hydrogen/deuterium (H/D) exchange (<1 degrees C, <30 s) was performed to examine pepsin cleavage specificity. The cleavage of pepsin was most influenced by the amino acid residue at position P1. Phe and Leu are favored residues each with a cleavage probability greater than 40%. His, Lys, Arg, or Pro residues prohibit cleavage when found at the P1 position. Pro also cannot be at position P2 (cleavage probability <0.3%). Occupation of the P3 position by His, Lys, or Arg, or occupation of the P2' position by Pro, also leads to very little cleavage (cleavage probability <1.7%). The average cleavage probability over the entire data set was 13.6%, which is slightly lower than the value previously obtained by Powers et al. (14.8%). This is due, in part, to the larger protein sizes used in the current study. While the specificity of pepsin was similar to that previously observed, higher selectivity was observed in the present study due to less experimental variation in the conditions used to generate our database.
对在与氢/氘（H/D）交换兼容的条件下（<1摄氏度，<30秒）用固定化猪胃蛋白酶消化的39种蛋白质（13766个氨基酸残基）的数据进行了统计分析，以研究胃蛋白酶的切割特异性。胃蛋白酶的切割受P1位氨基酸残基的影响最大。苯丙氨酸和亮氨酸是偏好的残基，各自的切割概率大于40%。当在P1位发现组氨酸、赖氨酸、精氨酸或脯氨酸残基时，会阻止切割。脯氨酸也不能位于P2位（切割概率<0.3%）。组氨酸、赖氨酸或精氨酸占据P3位，或脯氨酸占据P2'位，也会导致切割很少（切割概率<1.7%）。整个数据集的平均切割概率为13.6%，略低于Powers等人先前获得的值（14.8%）。这部分是由于本研究中使用的蛋白质尺寸较大。虽然胃蛋白酶的特异性与先前观察到的相似，但由于在生成我们数据库所使用的条件下实验变化较小，本研究中观察到了更高的选择性。
