Pelley J W, Little G H, Linn T C, Hall F F
Clin Chem. 1976 Feb;22(2):275-7.
Lipoamide dehydrogenase was identified in serum and the optimal conditions for its assay at 30 degrees C were defined. The pH optimum in tris(hydroxymethyl)aminomethane buffer is 7.8, and activity is inhibited if buffer concentration exceeds 100 mmol/liter. Saturating concentrations of the substrates NAD+ and lipoamide are 3 mmol/liter and 5 mmol/liter, respectively. Activity is decreased eightfold when lipoic acid is substituted for lipoamide. Activity is linearly related to enzyme concentration up to limiting absorbance change of 0.300 at 340 nm, and both within-day and day-to-day precision are satisfactory. Data suggest a normal range (2 SD) of 3-19 kU/liter. The highest value measured in serum was 473 kU/liter. A correlation with direct bilirubin concentrations (r equals 0.435, P less than 0.01) was found.
在血清中鉴定出硫辛酰胺脱氢酶，并确定了在30摄氏度下测定该酶的最佳条件。在三（羟甲基）氨基甲烷缓冲液中，最适pH值为7.8，如果缓冲液浓度超过100 mmol/升，酶活性会受到抑制。底物NAD⁺和硫辛酰胺的饱和浓度分别为3 mmol/升和5 mmol/升。当用硫辛酸替代硫辛酰胺时，酶活性降低八倍。在340 nm处，直至吸光度变化极限为0.300时，酶活性与酶浓度呈线性相关，日内和日间精密度均令人满意。数据表明正常范围（2个标准差）为3 - 19 kU/升。血清中测得的最高值为473 kU/升。发现与直接胆红素浓度存在相关性（r等于0.435，P小于0.01）。
