KING METHOD (E. J. King, Canadian biochemist, sort. in 1901) — the quantitative amiloklastichesky method of definition of activity of alpha amylase (KF 18.104.22.168) in serum and a blood plasma based on ability of the starch which is not split under the influence of enzyme during certain time in the presence of ions of iodine to be painted in blue-violet color. It is offered in 1947. Activity of amylase in blood serum increases at acute pancreatitis or at an aggravation hron, pancreatitis. Activity of amylase is determined by time necessary for splitting of the starch entered into reaction mixture. For the analysis use fresh serum or a blood plasma.
Main solution of iodine (0,1 N). Working solution of iodine is prepared just before experience, dissolving the main solution by 20 times. Solution of starch of 0,075%; store - it in the refrigerator no more than 5 — 7 days.
The course of definition
In a test tube is poured by 2 ml of solution of starch and put in the water bath at 37 °, in 2 min. bring 0,5 ml of plasma in a test tube or blood serum, mix and note time of the beginning of reaction. Each 2 — 5 min. select small tests on 0,1 — 0,2 ml and pour out them in the test tubes containing 0,2 ml of working solution of iodine. The end of reaction is noted on disappearance of blue-violet coloring and emergence of yellow coloring. At this moment hydrolysis of 1,5 mg of the starch which is contained in 2 ml of the taken solution of starch is considered ended.
Take its quantity catalyzing hydrolysis of 1,5 mg of starch within 8 min. (unit of King) for an activity unit of enzyme.
Calculation is carried out on a formula:
[the activity of amylase expressed in units on 100 ml of blood serum] = (8 • 100) / T • 0,5 = 1600T
where 0,5 — the amount of serum (or plasmas) blood entered into reaction mixture, T — time of reaction in minutes, 8 — time in min., necessary for splitting of 1,5 mg of starch the enzyme which is contained in 0,5 ml of plasma, activity of amylase in a cut is equal to 1 unit of King.
The healthy person has an activity of the amylase determined by this method, make 90 — 163 units of King on 100 ml of blood serum.
A shortcoming To. the m is difficulty of establishment of the exact time of the end of enzymatic reaction, and also need of repeated statement of staining reaction with iodine. See also Amylases .
Bibliography: Biochemical methods of a research in clinic, under the editorship of A. A. Pokrovsky, page 131, M., 1969; King E. J. Mic-го-analysis in medical biochemistry, p. 61, L., 1947.
L. H. Delektorskaya.