chemical properties
Alkaline phosphatase name
Alkaline phosphatase (ALP or AKP)
Secondary structure of bacterial alkaline phosphatase
Now ALP is widely used.
The system name is phosphate monoester phosphate dehydrogenase (alkaline best).
Other names include alkaline phosphomonoesterase; Phosphomonoesterase; Glycerol phosphatase; Alkaline phosphohydrolase; Alkaline phenyl phosphatase; Orthophosphate monoester phosphohydrolase (best alkaline); Alkaline phosphatase
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Alkaline phosphatase (AKP or alkaline phosphatase)
It belongs to homodimer protein with molecular weight of 56KDa. Each monomer consists of 449 amino acids. A complete AKP molecule presents a typical α/β topological structure, and each monomer has an active center. The active center is composed of ASP101-ser102-ala103 triplet, Arg 166, water molecules, three metal ions and their triplets. AKP is phoA? Like many secreted proteins, gene coding synthesizes monomer precursor with amino-terminal signal peptide in cytoplasm, and the signal peptide guides the precursor to transport through the inner membrane, and then it is excised to form homodimer.
Alkaline phosphatase is an enzyme that can dephosphorize the corresponding substrate, that is, phosphate groups on the substrate molecules are removed by hydrolyzing phosphate monoesters to generate phosphate ions and free hydroxyl groups. Such substrates include nucleic acids, protein, alkaloids, etc. The process of dephosphorization is called dephosphorization or dephosphorization Alkaline phosphatase is a kind of phosphatase, whose function is opposite to that of kinase, and it is phosphorylase. It can use energy molecules, such as ATP, to add phosphate groups to corresponding substrate molecules. Alkaline phosphatase is the most active in alkaline environment. For ALP from bacteria, its optimum pH is 8.0, while for ALP from cattle, its optimum pH is 8.5.
ALP is a glycoprotein containing zinc, which can hydrolyze a variety of natural and synthetic phosphate monoester substrates in alkaline environment (the optimum Ph is about 10).
Causes of high alkaline phosphatase
When the liver is damaged or disturbed, it will enter the blood through lymphatic channels and hepatic sinuses. At the same time, due to the obstruction of bile excretion in the biliary tract in the liver, the serum alkaline phosphatase will increase significantly. [ 1]
The causes of high alkaline phosphatase can be divided into physiological reasons and pathological reasons, which are discussed as follows:
1, physiological reasons, children's bone development, pregnant women, fracture healing period, in these cases, alkaline phosphatase in bone tissue is very active, so the detection time will be high.
2. Pathological causes of obstructive jaundice, primary liver cancer, secondary liver cancer and cholestatic hepatitis. Liver cells overproduce ALP and enter the blood through lymphatic channels and hepatic sinuses. At the same time, due to bile excretion disorder, alkaline phosphatase in serum is high.
3, when the bones are sick, such as rickets, bone tumors, rickets, etc.
4. Other less common diseases, such as nephropathy, severe anemia, thyroid dysfunction, leukemia, etc. [2].
What's the impact?
Alkaline phosphatase is mainly used for the examination of obstructive jaundice, primary liver cancer, secondary liver cancer and cholestatic hepatitis. It mainly enters the blood through lymphatic channels and hepatic sinuses, and at the same time, due to the obstruction of bile excretion in the biliary tract in the liver, it flows into the blood in the opposite direction, and the serum alkaline phosphatase is obviously increased. However, this enzyme is also active in bone tissue. Therefore, pregnant women, fracture healing, osteomalacia. When rickets, bone cancer, osteoporosis, liver abscess, liver tuberculosis, cirrhosis, leukemia, hyperthyroidism, serum alkaline phosphatase can also increase, so it is more harmful to human body.
Highly dangerous
Alkaline phosphatase (ALP) is a commonly used index in the diagnosis of biliary diseases. Alkaline phosphatase exists in all tissues of the body, especially in bones, liver and kidneys. Alkaline phosphatase in normal serum mainly comes from bone, which is produced by osteoblasts and excreted from biliary system to liver through blood. This enzyme was significantly increased in cholestatic hepatitis and extrahepatic obstruction. ALP can only indicate biliary obstruction, but can't distinguish whether the obstruction is benign or malignant. Generally more common in chronic liver.
High alkaline phosphatase indicates abnormal liver. When using high alkaline phosphatase, it may be liver cyst, liver tuberculosis, obstructive jaundice, secondary liver cancer and primary liver cancer. High alkaline phosphatase indicates osteopathy. When alkaline phosphatase is high, it may be osteomalacia, fracture healing period, bone cell carcinoma and bone metastasis of malignant tumor. High alkaline phosphatase indicates leukemia and hyperthyroidism.
How to reduce alkaline phosphatase;
Alkaline phosphatase is widely distributed in human bone, liver, intestine, placenta and other tissues. It is mainly used for the examination of obstructive jaundice, primary liver cancer, secondary liver cancer and cholestatic hepatitis. When suffering from these diseases, liver cells overproduce ALP, which enters human blood through lymphatic channels and hepatic sinuses. At the same time, due to bile excretion disorder of hepatobiliary duct, the serum alkaline phosphatase increased significantly. However, this enzyme is also active in bone tissue. Therefore, pregnant women, fracture healing, osteomalacia. When rickets, bone cancer, osteoporosis, liver abscess, liver tuberculosis, liver cirrhosis, leukemia, hyperthyroidism, serum alkaline phosphatase can also increase. You'd better do further examination to determine what causes the increase of alkaline phosphatase, and then carry out targeted treatment. I suggest that you use traditional Chinese medicines, such as Fructus Toosendan, Fructus Citri Sarcodactylis, Atractylodis Macrocephalae, Oak in August, Butterfly, Carapax et Plastrum Testudinis, Radix Paeoniae Alba, Hainan Ginseng, Korean Ginseng, Alismatis Rhizoma, Scutellariae Radix, Radix Aconiti Kusnezoffii powder, Poria, Bupleuri Radix, refined gold powder, sugar, honey and pig bile for treatment.
rise
A disease that can lead to an increase in alkaline phosphatase.
1. Hepatobiliary diseases: such as liver cirrhosis, liver cancer, hepatitis, extrahepatic biliary obstruction, etc. Can cause an increase in alkaline phosphatase.
2. Bone diseases: such as rickets, rickets, bone malignant tumors, etc. It will lead to an increase in alkaline phosphatase. When the bone is diseased, it will cause the increase of alkaline phosphatase [4].
source
The situation in the human body
Alkaline phosphatase is mainly used for the examination of obstructive jaundice, primary liver cancer, secondary liver cancer and cholestatic hepatitis. When suffering from these diseases, liver cells overproduce ALP, which enters the blood through lymphatic channels and hepatic sinuses. At the same time, due to the obstruction of bile excretion in the hepatobiliary duct, the serum alkaline phosphatase increased significantly. However, this enzyme is also active in bone tissue. Therefore, pregnant women, fracture healing, osteomalacia. When rickets, bone cancer, osteoporosis, liver abscess, liver tuberculosis, liver cirrhosis, leukemia, hyperthyroidism, serum alkaline phosphatase can also increase, which should be differentiated.
Research and application
Alkaline phosphatase is also one of the most commonly used marker enzymes in immunodiagnostic reagent products. Compared with horseradish peroxidase, ALP as a marker enzyme has the advantages of high stability and high sensitivity, but it has some disadvantages such as high cost and difficult labeling.
The most commonly used Alps in the study are as follows:
◇ bacterial alkaline phosphatase (BAP), source: Escherichia coli 4;
Shrimp alkaline phosphatase (SAP), source: a northern shad;
Calf fortified alkaline phosphatase from calf intestine;
◇? Placental alkaline phosphatase (PALP) and secretory alkaline phosphatase (SEAP), the latter is the C-terminal deficient type of the former-compared with PALP, SEAP does not have the last 24 amino acids at the C-terminal of PALP (these 24 amino acids and glycosylated phosphatidylinositol constitute a targeted anchoring region).
ALP is mainly used in molecular biology and enzyme immunoassay.
★ Mainly used for dephosphorylation of nucleic acids in molecular biology. Because DNA usually binds phosphate groups at the 5' end, dephosphorylation with ALP can prevent the connection between the 5' end and the 3' end of DNA molecules, so that the inhibition of DNA molecules is in a linear state before the subsequent steps are ready; Similarly, dephosphorylation can be used as a tracer for radioactive labeling. Shrimp alkaline phosphatase (SAP) is usually used for these purposes because it is most easily inactivated after the reaction is completed.
★ ELISA is the most widely used in enzyme immunoassay. Taking the detection of small molecule antigen by competition method as an example, firstly, the antibody is bound to the solid carrier, then the sample to be detected competes with the antigen labeled with ALP in advance to bind the antibody, the unreacted excess ALP- antigen is washed away, and the chromogenic substrate is added. Then, the concentration of antigen in the sample to be tested can be known by comparing it with the standard curve of concentration gradient drawn by the standard sample. Horseradish peroxidase (HRP) is commonly used in enzyme-linked immunosorbent assay. The substrate is OPD, which is dark orange and the detection wavelength is 492nm. TMB, blue-green, detects alkaline phosphatase with wavelength of 450nm. The substrate is PNPP (phosphoryl phosphate), yellow, and the detection wavelength is 405nm.
★ At present, it is widely used as a symbol of milk pasteurization in industry: molecules after pasteurization will be inactivated, and ALP substrate and milk without water bath sterilization will be added to them. After 2 minutes, the unsterilized sample should be yellow. If the sample to be tested (milk sterilized by water bath) can also show the same color, it means that the temperature of water bath sterilization is not too high. Of course, there are always exceptions, because a few bacteria will produce heat-resistant ALP.
Edit the determination method in this paragraph.
There are many kinds. Disodium phosphate colorimetry is widely used in China, but the continuous detection method is widely used at present.
The principle is that p-nitrophenol phosphate is used as the substrate, and 2- amino -2- methyl-1- propanol or diethanolamine is the acceptor of phosphate acyl. In alkaline environment, ALP catalyzes the hydrolysis of 4-NPP to generate free p-nitrophenol which turns yellow in alkaline solution. ALP activity unit was calculated according to the increase rate of absorbance at 405nm.
normal reach
Normal range (continuous monitoring method)
Female, 1- 12 years old, less than 500 u/l; /kloc-over 0/5 years old, 40-150 u/l;
Male, 1- 12 years old, less than 500 u/l; 12- 15 years old, less than 750 u/l; /kloc-over 0/5 years old, 40-150 u/l.
A high value may indicate bile duct obstruction; Low values are more common in children and pregnant women. A high value indicates that active bone deposition may occur because ALP is a by-product of osteoblast activity (osteogenesis) (for example, in the case of paget's disease [osteitis deformans]).
Generally speaking, low values are not as common as high values.
Clinical significance of editing this paragraph
The clinical determination of ALP is mainly used for the diagnosis and differential diagnosis of diseases of bone, hepatobiliary system, especially the differential diagnosis of jaundice. For unexplained high ALP serum levels, isoenzymes can be determined to help clarify the organ source.
1. Physiological increase: During physiological bone development, the activity of alkaline phosphatase in children is 1 ~ 2 times higher than that in normal people. Growing teenagers, pregnant women and eating foods with high fat content can all rise.
2. Pathological elevation:
(1) Bone diseases such as rickets, rickets, bone malignant tumor, bone metastasis of malignant tumor, etc.
(2) Hepatobiliary diseases such as extrahepatic biliary obstruction, liver cancer, liver cirrhosis, and capillary bile duct hepatitis.
(3) Other diseases such as hyperparathyroidism.
3. Pathological decrease: seen in severe chronic nephritis, thyroid insufficiency in children, anemia, etc.
Drug importance
Catalyze the hydrolysis of clindamycin phosphate to clindamycin, and make it play an antibacterial role.
Edit the abnormal reason of this paragraph.
Abnormal alkaline phosphatase is more common in obstructive jaundice, primary and secondary liver cancer, cholestatic hepatitis and so on. If it is hepatocellular jaundice, transaminase activity will be high, but alkaline phosphatase is slightly higher or normal. However, if it is obstructive jaundice, the opposite is true. Serum alkaline phosphatase will increase significantly, and transaminase will increase slightly. However, when liver cancer is ill, serum alkaline phosphatase is obviously increased, transaminase is not obviously increased and serum bilirubin is not high. [5]
Abnormal alkaline phosphatase is also found in bone diseases, such as osteogenesis imperfecta, fibrous osteitis, osteomalacia, fracture healing period and bone metastasis cancer.
Abnormal serum alkaline phosphatase may also be due to anemia and tumor, thyroid hypoplasia in children; Severe chronic nephritis and thyroid dysfunction; Vitamin C deficiency scurvy, celiac disease, cachexia, anemia and liver disease.
inhibitory action
High arginine can inhibit ALP isoenzymes in all mammals except placenta. Levamisole can inhibit all ALP isoenzymes except intestine and placenta. Except placental ALP(PALP and SEAP), almost all ALP can be inactivated at 65℃ for 2 hours.
Monoethanolamine has a temperature-dependent inhibitory effect on alkaline phosphatase;
Higher concentration of inorganic phosphorus can competitively inhibit the activity of alkaline phosphatase;
EDTA complexed with alkaline phosphatase, which led to the change of microenvironment conformation of enzyme activity center, thus irreversibly inhibited the activity of alkaline phosphatase.
Other inhibitors include benzidine (competitive), L- phenylalanine and dansyl -L- phenylalanine (anti-competitive), nitrogen-containing vanadium oxide complex (selective), pentachlorophenol (anti-competitive inhibition of human placental alkaline phosphatase) and so on. Hepatobiliary diseases
Hepatocytes participate in the synthesis of ALP, and the increased ALP in hepatobiliary diseases comes from hepatocytes.
The elevation of alkaline phosphatase in cholestatic diseases
ALP exists in microvilli on the surface of capillary bile duct, and the bile secretion increases obviously when it is disturbed. Due to bile acid stimulation, ALP mRNA translation increased and ALP synthesis in hepatocytes also increased. When ALP is excreted through bile and the bile ducts inside and outside the liver are blocked, ALP increases obviously, which appears before jaundice, and can continue to be abnormal after jaundice subsides.
Primary biliary cirrhosis, drug-induced hepatitis, liver transplantation rejection or intrahepatic cholestasis caused by cholestatic viral hepatitis will all increase ALP, even reaching 4 times the normal value.
Elevated alkaline phosphatase in intrahepatic space-occupying lesions
Even if there is no jaundice, the serum ALP can be increased in liver space-occupying lesions, including liver tumors and liver abscesses. The mechanism is unknown and may be related to the existence of small bile duct obstruction. In single lobular or segmental bile duct obstruction, the increase of serum alkaline phosphatase may be the only abnormal detection.
ALP is obviously increased in malignant tumors, and it is a marker enzyme of tumors. If the serum ALP is increased during the observation of the course of liver cirrhosis, the possibility of HCC should be considered.
Like other space-occupying lesions of the liver, serum ALP of liver metastases can be significantly increased. Some extrahepatic tumors can also synthesize ALP, which does not mean that extrahepatic tumors have liver metastasis.
Osteoblasts and alkaline phosphatase
The changes of osteoblast activity and osteogenesis are closely related to serum alkaline phosphatase activity. The increase of serum ALP in patients with osteopathy is mainly due to osteoblast proliferation. Abnormal osteitis is obviously increased, which is 10 to dozens of times of the upper limit of the normal reference value, but most of the serum calcium and phosphorus are normal. The changes of ALP in patients with rickets and osteomalacia are related to the course and condition. ALP increased slightly in the early stage, and continued to increase with the aggravation of the disease, reaching 4~ 10 times of the normal upper limit. After 2 weeks of treatment, the enzyme activity decreased. ALP activity increased slightly during fracture healing and significantly in patients with osteogenic bone cancer. There was no significant change in ALP of various types of osteoporosis and benign osteoblastoma. In patients with hyperparathyroidism, excessive parathyroid hormone leads to enhanced osteolysis, moderate or severe increase of ALP activity, increase of blood calcium and decrease of blood phosphorus. This is helpful to distinguish it from osteitis deformans and rickets.
The determination of serum ALP components shows that its main function is to distinguish whether the elevated ALP in serum comes from liver tissue alone or from bone tissue at the same time. ALP of liver type and bone type increases in blood at the same time, which is the most common in malignant tumors. The increase of hepatic alkaline phosphatase is almost the result of infiltration of liver malignant tumor. Secondary deposition of liver ALP in bone tissue can often cause osteogenic reaction, accompanied by the increase of bone ALP. Therefore, the proportion of serum liver type and bone type in patients with malignant tumor is high. Quantitative determination of ALP isoenzymes in liver type and bone type is of great value in judging the spread and curative effect of tumors.
Causes of low alkaline phosphatase
Alkaline phosphatase [6] can have both high symptoms and low symptoms. The causes of low alkaline phosphatase [6] can be mainly divided into the following categories:
1. Common in patients with severe chronic nephritis and thyroid insufficiency;
2. Malnutrition and dementia;
3. Vitamin C deficiency scurvy, celiac disease, cachexia and anemia;
4. Hereditary hypophosphatemia.
Although the phenomenon of low alkaline phosphatase is rare, it is mainly caused by pathological factors because of low alkaline phosphatase. So remind patients not to underestimate the occurrence of this symptom!
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