The Center for Cell Signaling & Drug Discovery Research, Ewha Womans University, Seoul 120-750, Republic of Korea.
J Chromatogr B Analyt Technol Biomed Life Sci. 2010 Mar 15;878(9-10):836-40. doi: 10.1016/j.jchromb.2010.01.034. Epub 2010 Jan 29.
A protease with broad substrate specificity usually produces a complex peptide mixture. However, even-numbered peptides were obtained at high proportion upon papain hydrolysis of fibroin composed of highly repetitive Ala- and Gly-rich blocks. MALDI-TOF and ESI mass spectrometric analysis revealed that the even-numbered peptides were in the forms of di-, tetra-, hexa-, and octa-peptides with repeating units in combination of Ala-Gly, Ser-Gly, Tyr-Gly, and Val-Gly. Application of tandem mass spectrometry identified the sequences of the tetra-peptides to be in the order of Ala-Gly-X-Gly (X = Tyr or Val). Therefore, the substrate specificity of papain and the unique repetitive sequence of fibroin generated the hydrolysate composed of even number of amino acids at a high percentage. In this work, fibroin hydrolysate was investigated as an example of an end product of protein hydrolysis, which provides a clue to understand the fate of peptides in a protein hydrolysate.
一种具有广泛底物特异性的蛋白酶通常会产生复杂的肽混合物。然而，在由高度重复的 Ala 和 Gly 丰富区组成的丝蛋白的木瓜蛋白酶水解中，却以高比例得到了偶数肽。MALDI-TOF 和 ESI 质谱分析表明，偶数肽是以 Ala-Gly、Ser-Gly、Tyr-Gly 和 Val-Gly 重复单元组合的二肽、四肽、六肽和八肽形式存在。串联质谱分析鉴定出四肽的序列按 Ala-Gly-X-Gly（X = Tyr 或 Val）的顺序排列。因此，木瓜蛋白酶的底物特异性和丝蛋白独特的重复序列生成了由偶数个氨基酸组成的水解产物，其百分比很高。在这项工作中，以丝蛋白水解产物为例研究了蛋白质水解的终产物，这为了解蛋白质水解产物中肽的命运提供了线索。
