Bowers P N, Bowers G N, McComb R B
Clin Chem. 1985 Jun;31(6):812-8.
We examined 17 lots of 2-oxoglutarate (seven acid forms, three K salt forms, and seven Na salt forms), obtained from eight commercial suppliers, for suitability for measuring aspartate aminotransferase (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2) in human serum. Measurements of the catalytic activity concentrations of these two aminotransferases with each of these 17 preparations were not sufficiently sensitive to distinguish good from poor-quality material. Thus, we ranked these lots for purity, by specific analysis with glutamate dehydrogenase and by liquid chromatography, and determined the water content, acid content, and spectral characteristics of each. On the basis of a 2-oxoglutarate assay value by glutamate dehydrogenase of 98% or greater, we considered seven of the preparations acceptable and 10 unacceptable. The molar absorptivities (L X mol-1 X cm-1, mean +/- SD) of the seven acceptable lots in 1 mol/L HCl were: epsilon 325 nm = 9.12 +/- 0.02 (CV = 0.2%), epsilon 279 nm = 2.63 +/- 0.23 (CV = 9.9%), and epsilon 245 nm = 37.9 +/- 4.1 (CV = 10.9%). Use of these spectrophotometric limits alone unambiguously distinguished the inferior lots of 2-oxoglutarate. We urge the inclusion of detailed spectrophotometric specifications for 2-oxoglutarate in Reference Methods for aminotransferase measurements.
我们检测了从八个商业供应商处获得的17批2-氧代戊二酸（七种酸形式、三种钾盐形式和七种钠盐形式），以确定其是否适合用于测定人血清中的天冬氨酸氨基转移酶（EC 2.6.1.1）和丙氨酸氨基转移酶（EC 2.6.1.2）。用这17种制剂分别测定这两种氨基转移酶的催化活性浓度，其灵敏度不足以区分质量好与质量差的材料。因此，我们通过谷氨酸脱氢酶的特异性分析和液相色谱法对这些批次的纯度进行了排名，并测定了每一批次的水分含量、酸含量和光谱特征。基于谷氨酸脱氢酶测定的2-氧代戊二酸含量值为98%或更高，我们认为其中七种制剂可接受，十种不可接受。七种可接受批次在1mol/L HCl中的摩尔吸光系数（L×mol-1×cm-1，平均值±标准差）分别为：ε325nm = 9.12±0.02（CV = 0.2%），ε279nm = 2.63±0.23（CV = 9.9%），ε245nm = 37.9±4.1（CV = 10.9%）。仅使用这些分光光度法限值就能明确区分劣质的2-氧代戊二酸批次。我们敦促在氨基转移酶测量的参考方法中纳入2-氧代戊二酸详细的分光光度法规范。
