Sasaki T, Morita T, Iwanaga S
J Biochem. 1986 Jun;99(6):1699-705. doi: 10.1093/oxfordjournals.jbchem.a135645.
A plasminogen-binding site of human alpha 2-plasmin inhibitor was studied. The chromatogram of digest from the amidinated alpha 2-plasmin inhibitor (67K-daltons, plasminogen-binding form) with trypsin was almost identical with that obtained from the 65K-daltons derivative (non-plasminogen-binding form) treated with the same procedure, except for the three tryptic peptides. One of the three peptides, the deamidinated peptide T-11, was found to have a strong ability to inhibit the interaction of alpha 2-plasmin inhibitor with human plasmin. Moreover, the dissociation constant Kd for interaction between the peptide T-11 and plasmin was estimated to be 5.5 microM, indicating that Kd is about 10-fold lower than that of epsilon-aminocaproic acid. The sequence of the peptide T-11 was determined by the Edman method as follows: NH2-G-D-K-L-F-G-P-D-L-K-L-V-P-P-M-E-E-D-Y-P-Q-F-G-S-P-K-COOH. alpha 2-Plasmin inhibitor and its 65K-daltons derivative were found to have the same NH2-terminal sequence of Asn(Asp)-Gln-Glu-Gln-. These results indicated that the plasminogen-binding site(s) of alpha 2-plasmin inhibitor could be located in the COOH-terminal region of its molecule and that some of epsilon-NH2-groups in the deamidinated peptide T-11 may be involved in the lysine-binding site(s) of plasmin(ogen).
对人α2 - 纤溶酶抑制剂的纤溶酶原结合位点进行了研究。用胰蛋白酶消化氨甲酰化的α2 - 纤溶酶抑制剂（67千道尔顿，纤溶酶原结合形式）得到的色谱图，与用相同方法处理的65千道尔顿衍生物（非纤溶酶原结合形式）得到的色谱图几乎相同，只是有三个胰蛋白酶肽段不同。这三个肽段之一，即脱酰胺化肽段T - 11，被发现具有很强的抑制α2 - 纤溶酶抑制剂与人类纤溶酶相互作用的能力。此外，肽段T - 11与纤溶酶相互作用的解离常数Kd估计为5.5微摩尔，这表明Kd比ε - 氨基己酸的Kd低约10倍。通过埃德曼法确定肽段T - 11的序列如下：NH2 - G - D - K - L - F - G - P - D - L - K - L - V - P - P - M - E - E - D - Y - P - Q - F - G - S - P - K - COOH。发现α2 - 纤溶酶抑制剂及其65千道尔顿衍生物具有相同的氨基末端序列Asn(Asp) - Gln - Glu - Gln - 。这些结果表明，α2 - 纤溶酶抑制剂的纤溶酶原结合位点可能位于其分子的羧基末端区域，并且脱酰胺化肽段T - 11中的一些ε - 氨基可能参与纤溶酶（原）的赖氨酸结合位点。
