Serine incorporation into the selenocysteine moiety of glutathione peroxidase.
Serine incorporation into the selenocysteine moiety of glutathione peroxidase.
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DOI：
10.1016/s0021-9258(19)75875-x
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发表时间：
1987-01
期刊：
影响因子：
--
通讯作者：
Roger A. SundeS;Jacqueline K. Evenson
中科院分区：
文献类型：
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作者：
Roger A. SundeS;Jacqueline K. Evenson
哺乳动物谷胱甘肽过氧化物酶中的硒以硒半胱氨酸([Se]Cys)的形式存在，从N末端进入肽骨架41-47个残基。为探讨[Se]半胱氨酸的骨架来源，我们用~(14)C和~(3+)标记氨基酸灌流大鼠离体肝4h，纯化GSH过氧化物酶，将GSH过氧化物酶中的[Se]半胱氨酸衍生化为羧甲基硒半胱氨酸([Se]Cys(Cm))，并测定其氨基酸比活力。用[14C]半胱氨酸灌流使[14C]半胱氨酸掺入GSH过氧化物酶，而不标记[Se]Cys(Cm)，表明半胱氨酸不是[Se]Cys的直接前体。在纯化的GSH过氧化物酶中，[14C]丝氨酸灌流标记丝氨酸、甘氨酸(丝氨酸羟甲基转移酶产物)和[Se]Cys(Cm)，而[3-~3H]丝氨酸灌流仅标记丝氨酸和[Se]Cys(Cm)，从而证明GSH过氧化物酶中的[Se]Cys来源于丝氨酸。丝氨酸和[Se]Cys(Cm)的相似比活性强烈地表明，用于合成[Se]Cys的丝氨酸库与用于酰化丝氨酰-tRNAs的丝氨酸库相同或相似。
The selenium in mammalian glutathione peroxidase is present as a selenocysteine ([Se]Cys) moiety incorporated into the peptide backbone 41-47 residues from the N-terminal end. To study the origin of the skeleton of the [Se]Cys moiety, we perfused isolated rat liver with 14C- or 3H-labeled amino acids for 4 h, purified the GSH peroxidase, derivatized the [Se]Cys in GSH peroxidase to carboxymethylselenocysteine ([Se]Cys(Cm)), and determined the amino acid specific activity. Perfusion with [14C]cystine resulted in [14C]cystine incorporation into GSH peroxidase without labeling [Se]Cys(Cm), indicating that cysteine is not a direct precursor for [Se]Cys. [14C]Serine perfusion labeled serine, glycine (the serine hydroxymethyltransferase product), and [Se]Cys(Cm) in purified GSH peroxidase, whereas [3-3H]serine perfusion only labeled serine and [Se]Cys(Cm), thus demonstrating that the [Se]Cys in GSH peroxidase is derived from serine. The similar specific activities of serine and [Se]Cys(Cm) strongly suggest that the precursor pool of serine used for [Se] Cys synthesis is the same or similar to the serine pool used for acylation of seryl-tRNAs.