Phosphatases intestinal

Intestinal alkaline phosphatase and human tissue non-specific alkaline phosphatase are two urinary isoenzymes that have ehcited interest as potential segment specific markers of the human nephron [190]. Both are members of the closely related group of alkaline phosphatases. Intestinal alkaline phosphatase is the intestinal isoenzyme that is locahzed on the brush border of human intestinal epithelial cells. It is also present in normal human kidney, where it is exclusively expressed on the brush border of tubulo-epithelial cells of the S3-segment of the proximal tubule. The intestinal alkaline phosphatase, which is released in urine, has its origin in the kidney. As a result, intestinal alkaline... 

Key words Alkaline phosphatase. Intestinal alkaline phosphatase. Tissue-nonspecific alkaline phosphatase, Placental alkaline phosphatase. High throughput assay, Chemilmninescence, CDP-star, Inhibition, Activation, Structure-activity relationship... 

Furthermore, incubation of APh-GDP with alkaline phosphatase (intestinal) and phosphodiesterase (snake venom) liberates 4-azidophenol. This leads to an increase in absorption at 303 nm. Incubation with phosphodiesterase alone produces APh-P, and incubation with alkaline phosphatase alone is without effect. 

Alkaline phosphatase intestines Carbonic anhydrase blood... 

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). 

TA Brasitus, R Dahiya, PK Dudeja, BM Bissonnette. Cholesterol modulates alkaline phosphatase activity of rat intestinal microvillus membranes. J Biol Chem 263 8592-8597, 1988. 

Alkaline phosphatases [AP, orthophosphoric-monoester phosphorylase (alkaline optimum) EC 3.1.3.1] represent a large family of almost ubiquitous isoenzymes found in organisms from bacteria to animals. In mammals, there are two forms of AP, one form present in a variety of tissues and another form found only in the intestines. They share common attributes in that the phosphatase activity is optimal at pH 8-10, is activated by the presence of divalent cations, and is inhibited by cysteine, cyanides, arsenate, various metal chelators, and phosphate ions. Most conjugates created with AP utilize the form isolated from calf intestine. 

Boge, G., M. Leydet, and D. Houvet. 1992. The effects of chromium on the activity of alkaline phosphatase in the intestine of rainbow trout (Oncorhynchus mykiss). Aquat. Toxicol. 23 247-260. 

Alkaline phosphatase levels and GGT are elevated in plasma with obstructive disorders that disrupt the flow of bile from hepatocytes to the bile ducts or from the biliary tree to the intestines in condition such as primary biliary cirrhosis, sclerosing cholangitis, drug-induced cholestasis, gallstone disease, and autoimmune cholestatic liver disease. 

Condensed (poly) phosphates may exert different effects on calcium utilization than the aforementioned effects of simple (ortho-) phosphates. Polyphosphates have a much greater affinity for calcium than do orthophosphates, and soluble calcium-polyphosphate complexes are readily formed in the gastric and intestinal environments. In addition, polyphosphates must be hydrolyzed by an intestinal alkaline phosphatase (27) prior to absorption. We have found polyphosphates to be incompletely (80.5%) hydrolyzed to orthophosphate during the digestive process in young adult males when calcium intake was low only 56% of a 1 g phosphorus supplement was absorbed from a polyphosphate sources as compared to 71% from an orthophosphate source (5). 

Enzyme labels are usually coupled to secondary antibodies or to (strept)avidin. The latter is used for detection of biotinylated primary or secondary antibodies in ABC methods (see Sect. 6.2.1). Enzyme labels routinely used in immunohisto-chemistry are horseradish peroxidase (HRP) and calf intestinal alkaline phosphatase (AP). Glucose oxidase from Aspergillus niger and E. coli (3-galactosidase are only rarely applied. 

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. 

Enzymatic markers used in immunohistochemistry Horseradish peroxidase (HRP) and calf intestinal or E.coli alkaline phosphatase (AP). Glucose oxidase from Aspergillus niger and E.coli /3-galactosidase are only rarely applied. 

Not all inhibitors fall into either of these two classes but some show much more complex effects. An uncompetitive inhibitor is defined as one that results in a parallel decrease in the maximum velocity and the Km value (Figure 8.8). The basic mode of action of such an inhibitor is to bind only to the enzyme-substrate complex and not to the free enzyme and so it reduces the rate of formation of products. Alkaline phosphatase (EC 3.1.3.1) extracted from rat intestine is inhibited by L-phenylalanine in such a manner. 

The example of amprenavir, an HIV-1 protease inhibitor, shows that intestinal metabolism can also be used as a strategy to enhance the bioavailability of compounds. In the biopharmaceutics classification system (BCS), amprenavir can be categorized as a class II compound it is poorly soluble but highly permeable [51]. Fosamprenavir, the water-soluble phosphate salt of amprenavir, on the other hand, shows poor transepithelial transport. However, after oral administration of fosamprenavir, this compound is metabolized into amprenavir in the intestinal lumen and in the enterocytes mainly by alkaline phosphatases, resulting in an increased intestinal absorption [51, 174],... 

Scheme 3 Dispensable phosphorylation of HDAC1. HDAC1 is posttranslationally phosphorylated. Upon phosphorylation, HDAC1 forms complexes with RbAp48 and mSinSA, which generate active HDAC1. When the protein complex is treated with calf intestinal phosphatase (CIP), the phosphates are removed, but activity and complex formation remain.

Okadaic acid is a powerful tumor promoter of a nonphorbol ester type that inhibits protein phosphatase-1 and -2A in vitro (Haystead et al., 1989). Okadaic acid directly stimulates smooth muscle contraction (Haystead et al., 1989) and probably causes diarrhea, either by stimulating the phosphorylation of proteins controlling sodium secretion by intestinal cells or by increasing phosphorylation of elements that regulate permeability to solutes, resulting in a passive loss of fluids (Aune and Yndestad, 1993). 

In addition to the enzymes that catalyse the formation of nucleotides and polynucleotides, a large number of catabolic systems exist which operate at all levels of the internucleotide pathways. The ribonucleases and deoxyribonucleases that degrade polynucleotides are probably not significantly involved in purine analogue metabolism, but the enzymes which dephosphorylate nucleoside 5 -monophosphates are known to attack analogue nucleotides and may be of some importance to their in vivo activity. Phosphatases of low specificity are abundant in many tissues [38], particularly the intestine [29]. Purified mammalian 5-nucleotidases hydrolyse only the nucleoside 5 monophosphates [28] and... 

Pantothenic acid occurs in foods both in the free form and bonded to coenzyme (CoA) or acyl carrier protein (ACP) therefore hydrolysis is needed to extract it totally. Since it is degraded by acid and alkaline hydrolysis, only an enzymatic digestion can be applied. Enzyme hydrolysis with papain, diastase, clarase, takadiastase, intestinal phosphatase, pigeon liver pantetheinase, or combination of them has been used. 

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