Rosano C, Arosio P, Bolognesi M
Centro Biotecnologie Avanzate-IST and Dipartimento di Fisica-INFM, University of Genova, Italy.
Biomol Eng. 1999 Dec 31;16(1-4):5-12. doi: 10.1016/s1050-3862(99)00047-9.
Avidin is a basic, highly stable, homotetrameric protein, isolated from bird egg-white, binding up to four molecules of D-biotin with extremely high affinity (Kd approximately 10(-15) M). The protein has been the object of different crystallographic investigations. In all the crystal structures, the four avidin subunits display almost exact 222 symmetry. Each avidin chain (128 amino acids) is arranged in a eight-stranded antiparallel beta-barrel, whose inner region defines the D-biotin binding site. The molecular bases of D-biotin affinity can be recognised in a fairly rigid binding site, which is sterically complementary to the shape and polarity of the incoming vitamin, and is readily accessible in the apoprotein structure. Avidin displays remarkable structural and functional relationships to the acidic protein sretpavidin, isolated from Streptomyces avidinii.
抗生物素蛋白是一种碱性、高度稳定的同四聚体蛋白，从鸡蛋清中分离得到，能以极高的亲和力（解离常数Kd约为10^(-15) M）结合多达四个D-生物素分子。该蛋白一直是不同晶体学研究的对象。在所有晶体结构中，四个抗生物素蛋白亚基几乎呈现出精确的222对称性。每个抗生物素蛋白链（128个氨基酸）排列成一个八链反平行β桶状结构，其内部区域定义了D-生物素结合位点。D-生物素亲和力的分子基础可在一个相当刚性的结合位点中识别，该位点在空间上与进入的维生素的形状和极性互补，并且在脱辅基蛋白结构中易于接近。抗生物素蛋白与从嗜热栖热放线菌中分离得到的酸性蛋白链霉抗生物素蛋白显示出显著的结构和功能关系。
