angiotensin converting enzyme

Angiotensin-converting enzyme (ACE), also known as kininase II or peptidyl-carboxypeptidase, is named peptidyl-dipeptide hydrolase. The vascular endothelial cell membrane-bound enzyme converts the amino acid into two stages from the C-terminus of the peptide, and can hydrolyze the C-terminal dipeptide residue of the peptide chain. ACE can catalyze the hydrolysis of angiotensin I (decapeptide) into an octapeptide angiotensin II, causing further contraction of blood vessels and an increase in blood pressure. It also acts on the adrenal cortex and promotes the secretion of aldosterone. Therefore, ACE is an important component of renin-angiotensin-aldosterone. ACE also catalyzes the hydrolysis of bradykinin with antihypertensive effects and loses activity. ACE is widely distributed in various tissues of the human body, and is rich in epididymis, testis and lung. Among them, pulmonary capillary endothelial cells have the highest ACE activity. Basic Information Specialist classification: cardiovascular examination classification: biochemical examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Serum ACE, such as asthma attack, acute cardiogenic pulmonary edema, chronic obstructive pulmonary disease, spontaneous pneumothorax, pulmonary fibrosis, and adult respiratory distress syndrome, decreased to varying degrees. High blood pressure, colitis, etc. are reduced. Normal value: Angiotensin-converting enzyme: 26.1-56.7kU/L Above normal: The majority of patients with sarcoidosis have elevated serum ACE activity, and the positive rate and extent are related to the extent of disease activity and the extent of lesion involvement, and tuberculosis can also be elevated. In most patients with liver disease, ACE activity increased, followed by cirrhosis, acute hepatitis, and chronic hepatitis. The ACE activity of patients with hyperthyroidism was significantly higher than that of other thyroid diseases, and the enzyme activity was positively correlated with T3 and T4 levels. Diabetes, iritis, immunoblastic sarcoma, etc., serum ACE increased. negative: Positive: Tips: Do not eat too greasy, high-protein foods the day before the blood draw, avoid heavy drinking. After 8 pm on the day before the medical examination, fasting should be done to avoid affecting the detection of indicators such as blood glucose in the second sky. Normal value 1. Sodium trinitrobenzene sulfonate (INBS) color development method 26.1 ~ 56.7kU / L. 2, enzyme coupling method 289 ± 83U / L. Clinical significance Serum ACE determination is mainly related to the diagnosis of lung diseases, and has certain value for the diagnosis and treatment of other system diseases. 1. Lung disease The majority of patients with sarcoidosis have elevated serum ACE activity, and the positive rate and extent are related to the extent of disease activity and the extent of lesion involvement. Tuberculosis can also be elevated, and serum ACE such as asthma attack, acute cardiogenic pulmonary edema, chronic obstructive pulmonary disease, spontaneous pneumothorax, pulmonary fibrosis, and adult respiratory distress syndrome have decreased to varying degrees. 2, liver disease In most patients with liver disease, ACE activity increased, followed by cirrhosis, acute hepatitis, and chronic hepatitis. Fatty liver is normal. 3, thyroid disease The ACE activity of patients with hyperthyroidism was significantly higher than that of other thyroid diseases, and the enzyme activity was positively correlated with T3 and T4 levels. 4, other Diabetes, iritis, immunoblastic sarcoma, etc., serum ACE increased; hypertension, colitis, etc. decreased. High results may be diseases: acute and chronic hepatitis, cirrhosis, chronic hepatitis 1, sodium trinitrobenzene sulfonate (INBS) color method: (1) The specimens were stored at room temperature or in the refrigerator for 1 week, and the enzyme activity did not change significantly. The enzyme activity was stable at -15 °C for 3 weeks. (2) Bilirubin has a significant inhibitory effect on ACE, so severe jaundice can make the measurement result low. EDTA is a strong inhibitor of ACE. NaCl and Na2SO4 have obvious activation effects on ACE. Hemolysis and lipemia have no effect on the results. (3) This method is consistent with the ultraviolet spectrophotometric enzyme activity unit, but its measured value is 9 times that of the ultraviolet method. 2. Enzyme coupling method: (1) When the substrate pH 8.0, GGCN 1.0 mmol/L, GGT 6.7 ku/L, the ACE activity and absorbance values ​​were linear. The linear range is large, and even if the ACE is at 1500 U/L, the desired result can be obtained without dilution. (2) GGCN concentration selection: GGCN in this reaction system is both a receptor for measuring enzyme ACE and a donor for GGT. It is most desirable to use 1.0 mmol/L of GGCN, at which the GGCN maintains good linearity with absorbance. (3) Effect of GGT on the measurement: This reaction uses GGT to couple the glyphosyl peptide to GGCN to form yellow 3-carboxy-4-nitroaniline, which can directly affect the measurement results. The high concentration of GGT can make the substrate excessively consumed, so that the absorbance deviates from the curve; the low concentration GGT makes the absorbance low and the sensitivity is not high. Ideal absorbance and linearity are achieved with 0.335 UGGT each time. At this concentration, the blank tube absorbance of the enzyme substrate solution was <0.1A. Inspection process 1. Sodium trinitrobenzene sulfonate (INBS) chromogenic method: Take 2 tubes, mark blank tube (B) and measuring tube (U), add 0.01 ml of serum, add tube B reagent (1), (3 ), (4), U tube plus substrate 0.1ml, set 37 ° C water bath 30min; U tube plus reagent (3), (4) each 0.1ml, then B, U tube each add distilled water 1.0ml, mix; 1500g Centrifuge for 10 min, take 0.75 ml of supernatant, add reagent (2) 1.0 ml and TNBS 0.05 ml, room temperature for 30 min or 37 ° C for 15 min, use 5 mm cuvette, at 420 nm, adjust B tube, read U tube Absorbance. 2. Enzyme coupling method: Take 4 small test tubes and indicate the measuring tube (U), standard tube (S), serum blank tube (SB), and reagent blank tube (RB). Mix well, adjust the zero point with double distilled water, and measure the absorbance ΔA of each tube for 2 min. Not suitable for the crowd no. Adverse reactions and risks no.