叠氮化钠氧化法测定生物组织中半胱氨酸含量

Determination of Sulphur-amino Acid Following Oxidation by Sodium Azide in Biological Samples

生物组织中的巯基活性重金属主要与半胱氨酸结合,是其代谢过程(如储存、转运和排泄等)主要存在形式。由于水解过程中半胱氨酸会被破坏,因此建立了一种氧化水解预处理方法,定量分析生物组织中的半胱氨酸。胱氨酸/半胱氨酸通过叠氮化钠氧化为磺基丙氨酸后,用氨基酸分析仪检测。结果表明,胱氨酸和磺基丙氨酸的定量限较低,分别为15 pmol和12 pmol;在10~200 nmol/mL浓度范围内有较好的线性关系(R 2>0.99)。胱氨酸和半胱氨酸的加标回收率均在90%以上。初级生产者半胱氨酸含量较低,然而不同消费者(如鱼类)肌肉组织中半胱氨酸含量差异不明显。综上所述,建立的基于叠氮化钠氧化水解法测定半胱氨酸含量的方法成熟可靠,可用于生物组织中胱氨酸/半胱氨酸含量的测定。

Sulfhydryl-reactive metals primarily bind to sulphur-amino acid during uptake,storage and elimination in organisms and was believed to be exclusively presented as metal-cysteine in muscle protein.An approach for the determination of cysteine following oxidation with sodium azide was developed,as cysteine was vulnerable to be destroyed during hydrolysis.Both cysteic acid and cystine were linear from 10 nmol/mL to 200 nmol/mL(R 2>0.99),with a detection limit of 15 pmol and 12 pmol,respectively.In addition,the recoveries of both cystine and cysteine were higher than 90%.The cysteine concentrations of wild-fish muscle samples were quantified using this method,and the results suggested no difference exist in cysteine concentrations among different fish species.Overall,performance characteristics of this method were reproducible and accurate,and this study provided a way for assessment the content of sulphur-amino acids in biological samples.