Wiman B, Wallén P
Eur J Biochem. 1975 Jan 15;50(3):489-94. doi: 10.1111/j.1432-1033.1975.tb09887.x.
Urokinase digestion of maleinated plasminogen results in cleavage of the single peptide bond Arg-68-Met-69, which is one of the bonds normally cleaved during the first step of the activation procedure. The inactive intermediate compound formed in this way was subjected to NH2-terminal amino acid sequence analysis, which clearly demonstrates the structural relationship between the forms of plasminogen with different NH2-terminal amino acids. It is thus shown that lysine-78 and valine-79 in the "glutamic acid" plasminogen actually are the NH2-terminal amino acids in "lysine" and "valine" plasminogen respectively. The forms with glutamic acid in NH2-terminal position are called plasminogen A, while all other forms lacking the NH2-terminal part of the molecule and which can be activated in a single step are called plasminogen B. By affinity chromatographic studies of the NH2-terminal activation peptide on insolubilized plasminogen B, it was demonstrated that this peptide has specific affinity for plasminogen B. It was also shown that this noncovalent interaction is broken by 6-aminohexanoic acid in two concentration. The tryptic heptapeptide (Ala-Phe-Gln-Tyr-His-Ser-Lys) which occupies the positions number 45 to 51 in the NH2-terminal activation peptide (as well as in the intact plasminogen molecule) is importance for the conformational state of the plasminogen molecule.
用尿激酶消化马来酰化的纤溶酶原会导致单一肽键精氨酸 -68 - 甲硫氨酸 -69 的断裂，这是激活过程第一步中通常会断裂的键之一。以这种方式形成的无活性中间化合物进行了氨基末端氨基酸序列分析，这清楚地表明了具有不同氨基末端氨基酸的纤溶酶原形式之间的结构关系。由此表明，“谷氨酸”纤溶酶原中的赖氨酸 -78 和缬氨酸 -79 实际上分别是“赖氨酸”和“缬氨酸”纤溶酶原中的氨基末端氨基酸。氨基末端位置为谷氨酸的形式称为纤溶酶原 A，而所有其他缺少分子氨基末端部分且可在一步中被激活的形式称为纤溶酶原 B。通过对固定化纤溶酶原 B 上的氨基末端激活肽进行亲和色谱研究，证明该肽对纤溶酶原 B 具有特异性亲和力。还表明这种非共价相互作用在两种浓度下都会被 6 - 氨基己酸破坏。在氨基末端激活肽（以及完整的纤溶酶原分子）中占据第 45 至 51 位的胰蛋白酶七肽（丙氨酸 - 苯丙氨酸 - 谷氨酰胺 - 酪氨酸 - 组氨酸 - 丝氨酸 - 赖氨酸）对纤溶酶原分子的构象状态很重要。
