Enzymatic method for assaying calcium in serum with Ca++-ATPase.
- Author:
Hassan Masood Ul JAVED
1
;
Francesco MICHELANGELI
Author Information
1. Department of Biochemistry The Aga Khan University, Karachi, Pakistan. masoodjaved@hotmail.com
- Publication Type:Original Article ; Comparative Study
- Keywords:
Ca++ -ATPase;
calcium;
serum;
enzymatic assay;
kinetics
- MeSH:
Adenosinetriphosphatase/metabolism;
Adolescent;
Adult;
Calcium/*blood;
Comparative Study;
Enzyme Activation;
Female;
Human;
Kinetics;
Male;
NAD/metabolism;
Pyruvate Kinase/metabolism;
Reference Standards;
Reproducibility of Results;
Sensitivity and Specificity
- From:Experimental & Molecular Medicine
2003;35(1):17-22
- CountryRepublic of Korea
- Language:English
-
Abstract:
A kinetic assay for total calcium in serum was developed which is based on the activation of Ca++-ATPase by free Ca++ [Ca++]f maintained by EGTA in the reaction mixture. The concentration of Caf++ 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).
