Imine Deaminase Activity and Conformational Stability of UK114, the Mammalian Member of the Rid Protein Family Active in Amino Acid Metabolism
Imine Deaminase Activity and Conformational Stability of UK114, the Mammalian Member of the Rid Protein Family Active in Amino Acid Metabolism
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DOI：
10.3390/ijms19040945
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发表时间：
2018-04-01
影响因子：
5.6
通讯作者：
Vanoni, Maria Antonietta
中科院分区：
文献类型：
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作者：
Degani, Genny;Barbiroli, Alberto;Vanoni, Maria Antonietta
活性中间体脱氨酶（Rid）蛋白家族是最近发现的一组在生命的所有领域中保守的酶，并且被认为在活性烯胺/亚胺的解毒中起作用。UK 114是RidA亚家族的哺乳动物成员，在90年代初被鉴定为羊肝高氯酸可溶性提取物的组分，具有免疫调节作用。该蛋白具有多种活性，但其功能尚不清楚。这项工作解决了UK 114是否是Rid酶的问题。生化分析表明，UK 114水解由L-或D-氨基酸氧化酶产生的α-亚氨基酸，优先水解来自Ala > Leu = L-Met > L-Gln的那些，而它对L-Phe和L-His的活性很差。UK 114构象稳定性的圆二色性（CD）分析突出了其即使在高尿素浓度下对热解折叠的显著抗性。根据CD和活性数据测量，95 ℃下热灭活的半衰期约为3.5小时。UK 114的不寻常的构象稳定性可能与其免疫原性的未来评估有关。总之，哺乳动物UK 114蛋白是RidA酶，可能在这些生物体的代谢稳态中发挥重要作用。
Reactive intermediate deaminase (Rid) protein family is a recently discovered group of enzymes that is conserved in all domains of life and is proposed to play a role in the detoxification of reactive enamines/imines. UK114, the mammalian member of RidA subfamily, was identified in the early 90s as a component of perchloric acid-soluble extracts from goat liver and exhibited immunomodulatory properties. Multiple activities were attributed to this protein, but its function is still unclear. This work addressed the question of whether UK114 is a Rid enzyme. Biochemical analyses demonstrated that UK114 hydrolyzes alpha-imino acids generated by L- or D-amino acid oxidases with a preference for those deriving from Ala > Leu = L-Met > L-Gln, whereas it was poorly active on L-Phe and L-His. Circular Dichroism (CD) analyses of UK114 conformational stability highlighted its remarkable resistance to thermal unfolding, even at high urea concentrations. The half-life of heat inactivation at 95 degrees C, measured from CD and activity data, was about 3.5 h. The unusual conformational stability of UK114 could be relevant in the frame of a future evaluation of its immunogenic properties. In conclusion, mammalian UK114 proteins are RidA enzymes that may play an important role in metabolism homeostasis also in these organisms.