|
An improved reagent system for chemical determinations and novel compositions therefor provide improved reagent stability, particularly in a dry, storage stable phase. For determinations in which hexokinase and glucose-6-phosphate dehydrogenase are indicator enzymes, glycine and taurine are combined with bovine serum albumin to provide a bulking agent for the indicator enzymes which also acts as a stabilizer. A novel salt, the tris (hydroxymethyl)aminomethane salt of 2 mercaptosuccinic acid, acts as an activator or stabilizer in chemistries utilizing the indicator enzymes, namely determinations of creatine phosphokinase or glucose. The novel salt also acts as a stabilizer in a urea nitrogen determination. Dry reagent components are bulked in triethanolammonium terepthalate. Novel CPK, glucose and serum urea nitogen determinations are also provided.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is initially discussed in the context of a CPK assay. All temperatures recited below are centigrade.
A CPK reagent system requires creatine phosphate substrate, ADP, magnesium activator, NAD, glucose, sulfhydryl activator compound such as glutathione or a different composition such as that provided in the present invention, hexokinase such as from a yeast source, and G-6-PDH from a leuconostoc source. Alternatively, NADP may be used in place of NAD, and the G-6-PDH utilized may be from a leuconostoc or yeast source. Additionally, buffer materials, AMP, filler, binder and stabilizers, particularly for the hexokinase and G-6-PDH, are required. In the preferred form, the stabilizer is also the filler.
EXAMPLE I
In the preferred form, it is desired to provide a dry powder CPK reagent system which is reconstituted for laboratory assay use. The following materials are dried in vacuo to constant weight. Each dry material is milled or ground to fine powder. The resulting dry powders are mixed such as by agitation in a ball mill, V-blender, or other mixer until samples withdrawn from the mix are found to be homogeneous. Operations and handling of materials should be performed under conditions in which atmospheric moisture will not be absorbed in or adsorbed to the materials so as to make the resulting reagent have a shorter life. The following components are utilized to make sufficient reagent to be reconstituted with 100 liters of water.
|
