Matsuka Y V, Novokhatny V V, Kudinov S A
Institute of Biochemistry, Academy of Sciences of the Ukranian SSR, Kiev.
Eur J Biochem. 1990 May 31;190(1):93-7. doi: 10.1111/j.1432-1033.1990.tb15550.x.
The ligand binding of kringle 1 + 2 + 3 and kringle 1 from human plasminogen has been investigated by fluorescence spectroscopy. Analysis of fluorescence titration of kringle 1 + 2 + 3 with 6-aminohexanoic acid shows that this fragment, besides the high-affinity lysine-binding site with Kd = 2.9 microM, contains two additional lysine-binding sites which differ in binding strength (Kd = 28 microM and Kd = 220 microM). This strongly suggests the existence of a lysine-binding site in each of the first three kringles. 6-Aminohexanoic acid, pentylamine, pentanoic acid and arginine were used for investigation of the ligand specificity of isolated kringle 1 prepared by pepsin hydrolysis of kringle 1 + 2 + 3. It has been established that kringle 1 has high affinity to 6-aminohexanoicacid, pentylamine and arginine (Kd values are 3.2 microM, 4.8 microM and 4.3 microM, respectively). At the same time pentanoic acid did not bind with kringle 1. These facts indicate, firstly, a broad ligand specificity of kringle 1 and, secondly, the paramount importance of the positively charged group of the ligand for its interaction with lysine-binding site of this kringle.
利用荧光光谱法研究了人纤溶酶原kringle 1 + 2 + 3和kringle 1的配体结合情况。用6 - 氨基己酸对kringle 1 + 2 + 3进行荧光滴定分析表明，该片段除了具有Kd = 2.9 μM的高亲和力赖氨酸结合位点外，还包含两个结合强度不同的赖氨酸结合位点（Kd = 28 μM和Kd = 220 μM）。这有力地表明在前三个kringle结构域中每个都存在一个赖氨酸结合位点。使用6 - 氨基己酸、戊胺、戊酸和精氨酸来研究通过胃蛋白酶水解kringle 1 + 2 + 3制备的分离的kringle 1的配体特异性。已经确定kringle 1对6 - 氨基己酸、戊胺和精氨酸具有高亲和力（Kd值分别为3.2 μM、4.8 μM和4.3 μM）。同时，戊酸不与kringle 1结合。这些事实表明，首先，kringle 1具有广泛的配体特异性；其次，配体的带正电荷基团对于其与该kringle的赖氨酸结合位点的相互作用至关重要。
