Perreault Amanda, Knight James C, Wang Monica, Way Jenilee, Wuest Frank
Department of Oncology, University of Alberta, Edmonton, AB, T6G 1Z2, Canada.
Amino Acids. 2016 Jan;48(1):65-74. doi: 10.1007/s00726-015-2068-0. Epub 2015 Aug 9.
Early stage apoptosis is characterized by the externalization of phosphatidylserine (PS) from the inner leaflet of the plasma membrane to the outer periphery. Consequently, PS represents an excellent target for non-invasive imaging of apoptosis by positron emission tomography. Annexin V is a 36 kDa protein which binds with high affinity to PS. Radiolabeling of wild-type annexin V with fluorine-18 ((18)F) can be accomplished via random acylation of 23 amine groups (22 lysine residues and one N-terminal amine) with [(18)F]SFB or site-specific alkylation reaction on cysteine residue at position 315 with maleimide-containing prosthetic groups like [(18)F]FBEM. The effect upon random and site-directed (18)F labeling of annexin V was studied with EL4 mouse lymphoma cells. Both, randomly and site-selectively radiolabeled annexin V demonstrated comparable binding to apoptotic EL4 cells. This finding suggests that the (18)F radiolabeling method has no significant effect on the ability of (18)F-labeled wild-type annexin V to bind PS in apoptotic cells.
早期凋亡的特征是磷脂酰丝氨酸（PS）从质膜内小叶外化至外周。因此，PS是通过正电子发射断层扫描对凋亡进行非侵入性成像的极佳靶点。膜联蛋白V是一种36 kDa的蛋白质，它与PS具有高亲和力结合。用氟-18（¹⁸F）对野生型膜联蛋白V进行放射性标记可通过用[¹⁸F]SFB对23个胺基（22个赖氨酸残基和一个N端胺基）进行随机酰化，或用含马来酰亚胺的 Prosthetic 基团如[¹⁸F]FBEM对315位的半胱氨酸残基进行位点特异性烷基化反应来完成。用EL4小鼠淋巴瘤细胞研究了¹⁸F对膜联蛋白V随机标记和定点标记的影响。随机和位点选择性放射性标记的膜联蛋白V与凋亡的EL4细胞均表现出相当的结合能力。这一发现表明，¹⁸F放射性标记方法对¹⁸F标记的野生型膜联蛋白V在凋亡细胞中结合PS的能力没有显著影响。
