Liver enzymes alkaline phosphatase

Chronic rejection of the liver is characterized by an obliterative arte-riopathy and the loss of bile ducts, which has been referred to as the vanishing bile duct syndrome. These patients experience an asymptomatic rise in the canalicular liver enzymes (alkaline phosphatase and Y -glutamyl transpeptidase) and become j aundiced. These changes are considered the result of immunologic and ischemic injmy and can be seen in patients who have not responded adequately to therapy for acute rejection. 

Serum biochemistry methods were used to evaluate the toxic effect of the procedure. The parameters evaluated include concentrations of major ions (Na+,K+,C1 ) major proteins (albumin and total protein) liver-specific enzymes (alkaline phosphatase ALP) aspartate aminotransferase (AST), alanine aminotransferase (ALT)... 

Today, for the purpose of illustrating these points, we wish to review selected segments of work performed in our laboratory on two multichain enzymes—alkaline phosphatase from . coli and equine liver alcohol dehydrogenase—in which intrinsic metal atoms appear to play both functional and structural roles. Thereafter, we hope to discuss data suggesting that metals may be important also to the structure of certain single-chain proteins and to the general phenomenon of stabilization of protein structure. 

Cocoa powder exerted anticancer properties in in vivo studies. Amin et al. [50] indicated that cocoa liquor extract lowered the activity of tumor marker enzymes (alkaline phosphatase, gamma-glutamyl transpeptidase, glutathione-S-transferase, and glutathione reductase activities) in plasma and/or liver of hepatocarcinogenic male Sprague-Dawley rats, which were induced with diethylnitrosamine and 2-acetylaminofluorene. 

Alkaline phosphatase assays based on 3-glycerophosphate now appears to be obsolete, and methods buffered by either glycine or barbital are also obsolete as these buffers inhibit ALP or are poor buffers. Serum alkaline phosphatase is known to be composed of several isoenzymes which presumably arise from bone, liver, intestine, and placenta. The placental alkaline phosphatase is known to be much more resistant to heat denaturation than the other isoenzymes, and this resistance provides a simple test for it (5). The other enzymes can be separated through the differential inhibition by phenylalanine, by electrophoresis and by specific antibodies. However, the clinical usefulness of the results obtained is in doubt (23). 

The enzymes found in liver cells (Group I enzymes) include more than a dozen enzymes used in diagnostic laboratories, but those used most commonly are the transaminases (GOT and GPT), which continue to be the most widely used indicators of liver cell integrity. Enzymes found in the biliary cells (Group II) include alkaline phosphatase, glutamyl-transferase, leucine amniopeptidase and 3-nucleotidase. 

Pantothenate in blood and tissues is bound (R9) and released by autolysis or hydrolysis. More vitamin could be released by use of an alkaline phosphatase and an enzyme from avian liver (L6). This method liberates pantothenate from coenzyme A in a variety of foods and tissues (N3, N4). A comparison of hydrolytic methods in blood suggested autolysis to be the most advantageous method (N3) in our hands, treatment with Clarase gave more reliable results as compared with autolysis, acid hydrolysis, treatment with Mylase P, or combination of Clarase and papain, or liver enzyme and alkaline phosphatase. In urine, pantothenic acid is unbound our results show no increase with Clarase treatment. The vitamin has presumably a low threshold. Pantothenic acid shows the same concentration in blood and cerebrospinal fluid. 

Alkaline phosphatase is an enzyme represented by various isoforms in many tissues such as liver, bone, intestine, placenta, some tumors and in leukocytes. Addition of 1 mM levamisole to the chromogen/substrate will inhibit endogenous alkaline phosphatase activity, with the exception of the intestinal isoform. If necessary, this can be blocked with a weak acid wash, such as 0.03 0.5 N HC1 or 1 M citric acid. 

Phosphates of pharmaceutical interest are often monoesters (Sect. 9.3), and the enzymes that are able to hydrolyze them include alkaline and acid phosphatases. Alkaline phosphatase (alkaline phosphomonoesterase, EC 3.1.3.1) is a nonspecific esterase of phosphoric monoesters with an optimal pH for catalysis of ca. 8 [140], In the presence of a phosphate acceptor such as 2-aminoethanol, the enzyme also catalyzes a transphosphorylation reaction involving transfer of the phosphoryl group to the alcohol. Alkaline phosphatase is bound extracellularly to membranes and is widely distributed, in particular in the pancreas, liver, bile, placenta, and osteoplasts. Its specific functions in mammals remain poorly understood, but it seems to play an important role in modulation by osteoplasts of bone mineralization. 

Serum alkaline phosphatase elevations have been reported following administration of salt-poor albumin (B5). Placenta is very rich in a heat-stable alkaline phosphatase, and albumin prepared from placental blood has a high activity of this enzyme. In one cirrhotic patient who received 1-6 units per day of albumin obtained from pooled human blood and/or human placenta, the alkaline phosphatase before infusion was 5 Bodansky units and by the thirteenth day of administration had reached a value of 160 units. The physician administering the albumin at first thought the patient was having a severe toxic liver reaction and stopped the therapy. The alkaline phosphatase then started to go down and within 10 days returned to normal levels. Analysis of the albumin indicated that it contained 470 units of alkaline phosphatase activity and was probably responsible for the observed elevations in the serum enzyme activity. Albumin prepared from venous blood did not cause an alkaline phosphatase elevation, but placenta-albumin caused elevations with a half-life of about 8 days (Ml). 

Adverse reactions occurring in at least 3% of patients included the following abnormal vision, alkaline phosphatase increased, ALT/AST increased, chills, fever, hallucinations, headache, hepatic enzymes increased, liver function test abnormal, nausea, peripheral edema, photophobia, rash, vomiting. 

Blood glucose, liver enzymes, and serum alkaline phosphatase, bilirubin, and potassium, AST (SCOT), and ALT (SGPT) levels... 

The frequent occurrence of sialylated enzymes, or even of multiple forms, which are sometimes tissue-dependent, with a varying number of sialyl residues as, for example, in y-glutamyltranspeptida.se (EC 2.3.2.2),456,457 is not yet fully understood. Although the activity of most of these enzymes is not influenced by removal of sialic acid,454 the activity of monoamine oxidase A (EC 1.4.3.4) of outer mitochondrial membranes of rat liver has been shown to be destroyed by treatment with sialidase438 the substrate specificity of acetylcholinesterase (EC 3.1.1.7) is altered,459 the kinetic properties of human acid and alkaline phosphatases (EC 3.1.3.1 and 3.1.3.2) are changed, and the stability of a-D-galactosidase (EC 3.2.1.22) is drastically lowered.415 In these cases, an influence of sialyl residues on the conformation of the enzyme is assumed, but awaits firm evidence. 

Instead of using human serum albumin as a carrier protein, other workers (135) utilized ovalbumin for preparing the diazotized clenbuterol antigen in an enzyme immunoassay developed for screening of clenbuterol residues in bovine urine, liver, and eye. Alkaline phosphatase rather than -galactosidase was also used as an enzyme label in the preparation of the enzyme-clenbuterol conjugate. 

By analysis of the products with glucose oxidase, it was shown that the anomeric composition of the glucose liberated from glucose-6-phos-phate by the enzymes acid or alkaline phosphatase or by glucose-6-phosphatase from rat liver was essentially the same as that of the substrate, thus indicating a lack of anomeric specificity for these enzymes also (106). 

These enzymes, which mainly catalyze hydrolytic reactions, have the zinc ions at their active sites. However, Zn ions also appear necessary in some cases for stabilization of the protein structure, e.g. in Cu/Zn SOD, insulin, liver alcohol dehydrogenase and alkaline phosphatases. 

At room temperature alkaline phosphatases are generally stable in neutral or mildly alkaline solution but are sensitive to inactivation by acid. Unfortunately, most stability data refer to impure preparations and some of the following statements may need modifying when further information is available. Scutt and Moss investigated the denaturation of human liver and intestinal enzymes at pH 2.1 and 0° (92). The liver enzyme was significantly more labile, and both enzymes could be par-... 

Anagnostopoulos found that the amino group reagents ketene, nitrous acid, formaldehyde, and phenyl isocyanate all inactivated bovine liver and kidney phosphatases 102). On the other hand, acetylation of chicken intestinal phosphatase with acetic anhydride gave an active product with optimum activity more alkaline than normal 103). The enzyme preparation was impure and acetylation only 70% complete... 

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