| 摘要 |
Chloride ion and sodium ion determination methods, compositions, and assays are provided which are based on the use of sodium ion as an activator for alpha-amylase. Chloride ion and sodium ion determination are performed by colorimetry, using measurements of alpha-amylase activity to indirectly measure the desired ion concentrations. One preferred composition for chloride ion determination comprises alpha-amylase that is substantially calcium free, sodium ion in higher concentration than the alpha-amylase, and an alpha-amylase activity detecting substrate. In the methods, alpha-amylase is deactivated by a calcium-binding compound, thereby preventing calcium from bonding with the alpha-amylase. Next, chloride ion and sodium ion stoichiometrically bond with deactivated alpha-amylase, thereby activating the alpha-amylase. Chloride ion determination methods are based on using test sample chloride as the limiting factor in alpha-amylase activation and sodium ion determination methods are based on using test sample sodium as the limiting factor in alpha-amylase activation.
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