Javed Masood-ul-Hassan, Michelangeli Francesco
Department of Biochemistry, The Aga Khan University, Karachi, Pakistan.
Exp Mol Med. 2003 Feb 28;35(1):17-22. doi: 10.1038/emm.2003.3.
A kinetic assay for total calcium in serum was developed which is based on the activation of Ca(++)-ATPase by free Ca(++) Ca(++) maintained by EGTA in the reaction mixture. The concentration of Ca(++)(f) was dependent on total reference calcium added or serum calcium. Ca(++)-ATPase activity was coupled to the reduction of NADH by pyruvate kinase (PK) and lactate dehydrogenase (LDH) and monitored by change in absorbance at 340 nm. The calcium in normal serum was 10.08 +/- 0.24 mg/dl (n = 35) by our method while with o-cresolphthalein complexone (CPC) method, the total calcium in the same 35 serum samples was 10.14 +/- 0.54 mg/dl. The range of within-run coefficient of variations (CVs) by this method was 0.9-2.87% at 8-12 mg/dl and day-to-day CVs were 0.72-3.17%. The presence of other ions and standard clinical interfering agents did not affect this assay system. The correlation between values obtained with our method (y) and CPC method (x) for normal serum was: y = 1.064x-0.580 mg/dl (r = 0.912, n = 59).
建立了一种血清总钙的动力学测定方法，该方法基于反应混合物中由乙二醇双（2-氨基乙基醚）四乙酸（EGTA）维持的游离Ca(++)Ca(++)对Ca(++)-ATP酶的激活作用。Ca(++) (f)的浓度取决于添加的总参比钙或血清钙。Ca(++)-ATP酶活性通过丙酮酸激酶（PK）和乳酸脱氢酶（LDH）与NADH的还原反应偶联，并通过340nm处吸光度的变化进行监测。用我们的方法测得正常血清中的钙为10.08±0.24mg/dl（n = 35），而用邻甲酚酞络合酮（CPC）法测得相同35份血清样本中的总钙为10.14±0.54mg/dl。该方法在8 - 12mg/dl时批内变异系数（CVs）范围为0.9 - 2.87%，日间CVs为0.72 - 3.17%。其他离子和标准临床干扰剂的存在不影响该测定系统。正常血清用我们的方法（y）和CPC法（x）测得的值之间的相关性为：y = 1.064x - 0.580mg/dl（r = 0.912，n = 59）。
