Pfaff M, McLane M A, Beviglia L, Niewiarowski S, Timpl R
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Cell Adhes Commun. 1994 Dec;2(6):491-501. doi: 10.3109/15419069409014213.
The inhibitory capacities of six different disintegrins and one related neurotoxin analogue for the binding of RGD-dependent integrins to either fibrinogen, vitronectin or fibronectin were compared in solid phase assays. Echistatin and flavoridin were the most active inhibitors for alpha V beta 3 and alpha 5 beta 1 integrins and moderately exceeded the activity of the natural protein ligands. The same disintegrins together with eristostatin, bitistatin and barbourin were also very potent inhibitors of fibrinogen binding to alpha IIb beta 3 integrin. For all three integrins, albolabrin showed the lowest affinity, but it still clearly exceeded that of synthetic GRGDS. However, assay conditions may determine these relative affinities, as shown for the alpha IIb beta 3 and alpha V beta 3 integrins when used either in immobilized or soluble form. For alpha IIb beta 3, however, a close correlation was found between KD values determined in platelet binding assays and the concentrations required for half maximal inhibition of three disintegrins. The inhibiting capacity of disintegrins in assays with purified integrins also correlated reasonably well with their inhibition of cell attachment to RGD-dependent protein substrates. However, sequence differences in the RGD loops of the various disintegrins may not fully account for the 20-100-fold difference in their binding capacities. This was particularly evident for echistatin and albolabrin, which differ in this region only by two conservative substitutions but have considerably different inhibitory activities. More remote regions of the disintegrins and alignment of disulfide bridges are therefore likely to contribute to their affinity and selectivity.
在固相分析中比较了六种不同的去整合素和一种相关神经毒素类似物对RGD依赖性整合素与纤维蛋白原、玻连蛋白或纤连蛋白结合的抑制能力。echistatin和flavoridin是αVβ3和α5β1整合素最有效的抑制剂，其活性略高于天然蛋白质配体。同样的去整合素与eristostatin、bitistatin和barbourin一起也是纤维蛋白原与αIIbβ3整合素结合的非常有效的抑制剂。对于所有三种整合素，albolabrin显示出最低的亲和力，但仍明显高于合成的GRGDS。然而，检测条件可能会决定这些相对亲和力，如αIIbβ3和αVβ3整合素以固定化或可溶性形式使用时所示。然而，对于αIIbβ3，在血小板结合试验中测定的KD值与三种去整合素半数最大抑制所需浓度之间发现密切相关。在纯化整合素的分析中，去整合素的抑制能力也与其对细胞黏附于RGD依赖性蛋白质底物的抑制作用有合理的相关性。然而，各种去整合素RGD环中的序列差异可能无法完全解释它们结合能力20至100倍的差异。这在echistatin和albolabrin中尤为明显，它们在该区域仅相差两个保守取代，但具有相当不同的抑制活性。因此，去整合素更偏远的区域和二硫键的排列可能有助于它们的亲和力和选择性。
