Green N M, Konieczny L, Toms E J, Valentine R C
Biochem J. 1971 Dec;125(3):781-91. doi: 10.1042/bj1250781.
A series of bisbiotinyl diamines was synthesized with between 9 and 25 bonds between the carboxyl groups of the two biotin residues. It was found that only one of the two biotin residues could combine with avidin when there were fewer than 12 bonds between the biotin residues. Compounds with longer chains behaved in a bifunctional manner and gave rise to linear polymers of avidin, which were characterized by electron microscopy and by gel filtration. The polymers formed with the shorter-chain reagents (12, 13 or 14 bonds) were relatively unstable and could be depolymerized by weakly bound analogues of biotin. The polymers of longer-chain reagents were not depolymerized under these conditions and were only slowly affected by added biotin. When the chain length of the reagent reached 23 bonds the polymers became much shorter, suggesting that the reagent was now able to link two subunits within the same avidin molecule. From the morphology of the polymers it could be concluded that the four subunits of the avidin molecules were arranged with 222 symmetry and that they were grouped in two pairs at opposite ends of the short axis of the molecule whose dimensions were 55Ax55Ax41A.
合成了一系列双生物素基二胺，两个生物素残基的羧基之间有9至25个键。研究发现，当生物素残基之间的键少于12个时，两个生物素残基中只有一个能与抗生物素蛋白结合。链较长的化合物表现出双功能特性，并产生抗生物素蛋白的线性聚合物，通过电子显微镜和凝胶过滤对其进行了表征。用较短链试剂（12、13或14个键）形成的聚合物相对不稳定，可被生物素的弱结合类似物解聚。在这些条件下，较长链试剂形成的聚合物不会解聚，只是受到添加的生物素的缓慢影响。当试剂的链长达到23个键时，聚合物变得短得多，这表明该试剂现在能够连接同一抗生物素蛋白分子内的两个亚基。从聚合物的形态可以得出结论，抗生物素蛋白分子的四个亚基以222对称排列，它们在分子短轴的相对两端成对聚集，分子尺寸为55Å×55Å×41Å。
