Effects of amines and aminoalcohols on bovine intestine alkaline phosphatase activity

Bovine intestine alkaline phosphatase (BIALP) is widely used as a signaling enzyme in sensitive assays such as enzyme immunoassay (EIA). In this study, we evaluated the effects of various aminoalcohols and amines on the activity of BIALP in the hydrolysis of p-nitrophenyl phosphate (pNPP) at pH 9.8, at 20 °C. The k_cat values at 0.05 M diethanolamine, 0.1 M triethanolamine, and 0.2 M N-methylethanolamine were 190 ± 10, 840 ± 30, and 500 ± 10 s⁻¹, respectively. The k_cat values increased with increasing concentrations of diethanolamine, triethanolamine, and N-methylethanolamine and reached 1240 ± 60, 1450 ± 30, and 2250 ± 80 s⁻¹, respectively, at 1.0 M. On the other hand, the k_cat values at 0.05-1.0 M ethanolamine, ethylamine, methylamine, and dimethylamine were in the range of 100-600 s⁻¹. These results indicate that diethanolamine, triethanolamine and N-methylethanolamine highly activate BIALP and might be suitable as a dilution buffer of BIALP in EIA. Interestingly, the K_m values increased with increasing concentrations of diethanolamine and N-methylethanolamine, but not triethanolamine: the K_m value at 1.0 M diethanolamine (0.83 ± 0.15 mM) was 12-fold higher than that at 0.05 M (0.07 ± 0.01 mM), and that at 1.0 M N-methylethanolamine (2.53 ± 0.20 mM) was 14-fold higher than that at 0.2 M (0.18 ± 0.02 mM), while that at 1.0 M triethanolamine (0.31 ± 0.01 mM) was similar as that at 0.2 M (0.25 ± 0.01 mM), suggesting that the mechanisms of BIALP activation are different between the aminoalcohols.     

Effects of polyethylene glycol on bovine intestine alkaline phosphatase activity and stability

In this study, we evaluated the effects of polyethylene glycol (PEG) on bovine intestine alkaline phosphatase (BIALP) activity and stability. In the hydrolysis of p-nitrophenylphosphate (pNPP) at pH 9.8 at 20 °C, the k(cat)/K(m) values of BIALP plus 5-15% w/v free PEG with molecular masses of 1, 2, 6, and 20 kDa (PEG1000, PEG2000, PEG6000, and PEG20000 respectively) were 120-140%, 180-300%, 130-170%, and 110-140% respectively of that of BIALP without free PEG (1.8 μM(-1) s(-1)), indicating that activation by PEG2000 was the highest. Unmodified BIALP plus 5% PEG2000 and BIALP pegylated with 2,4-bis(O-methoxypolyethylene glycol)-6-chloro-s-triazine exhibited 1.3-fold higher activity on average than that of BIALP without free PEG under various conditions, including pH 7.0-10.0 and 20-65 °C. The temperatures reducing initial activity by 50% in 30-min incubation of unmodified BIALP plus 5% PEG2000 and pegylated BIALP were 51 and 47 °C respectively, similar to that of BIALP without free PEG (49 °C). These results indicate that the addition of PEG2000 and pegylation increase BIALP activity without affecting its stability, suggesting that they can be used in enzyme immunoassay with BIALP to increase sensitivity and rapidity.     

Isozymes of bovine intestinal alkaline phosphatase

Alkaline phosphatases from calf and bovine small intestines have been isolated in homogeneous form from both mucosa and luminal contents. The detergent-solubilized calf enzyme resolves into two peaks of activity, C-1 and C-2, on chromatofocusing. Only one of these activity peaks is present in the enzyme from the adult animal. Amino acid compositions, N-terminal sequences, and tryptic peptide maps show that C-1 and C-2 are isozymes of differing primary structure and that the adult form of the enzyme is identical to C-2. The developmentally controlled expression of the two isozymes reported here suggests a molecular basis for the previous indications that functional changes in intestinal alkaline phosphatase occur with tissue maturation. The sugar composition of the carbohydrate chains of these isozymes has been determined and enzymatic deglycosylation with endo-beta-N-acetylglucosaminidase-F indicates two N-linked and one or more O-linked glycoconjugates/monomer.     

Affinity-chromatography purification of alkaline phosphatase from calf intestine.

A crude preparation of alkaline phosphatase (EC 3.1.3.1) from calf intestinal mucosa was purified by affinity chromatography on Sepharose-bound derivatives of arsanilic acid, which was found to be a competitive inhibitor of the enzyme. Three biospecific adsorbents were prepared for the chromatography, and the best results were obtained with a tyraminyl-Sepharose derivative coupled with the diazonium salt derived from 4-(p-aminophenylazo)phenylarsonic acid. Alkaline phosphatase was the only enzyme retained by the affinity column in the absence of Pi. The enzyme eluted by phosphate buffer had a specific activity of about 1200 units per mg of protein at pH 10.0, with 5.5mM-p-nitrophenyl phosphate as the substrate.     

Characterization of alkaline phosphatase from bovine polymorphonuclear neutrophils

We characterized the bovine polymorphonuclear neutrophil alkaline phosphatase which was considerably purified with a sp. act. of 206 units/mg of protein. The Km value for p-nitrophenylphosphate at pH 10.0 was 1.69 mM. L-Histidine, imidazole and L-homoarginine but not L-phenylalanine inhibited the enzyme. In heat stability study, the enzyme lost 50% activity at 56 degrees C for 20 min. The enzyme had a half-life of 30 min in 3 M urea at 37 degrees C and pH 7.5. The enzyme was inhibited by beta-mercaptoethanol in a dose-dependent fashion. It is suggested from above results that the neutrophil alkaline phosphatase isozyme could be distinguishable from other tissue isozymes.     

Physico-chemical properties of alkaline phosphatase from the seal small intestine

Alkaline phosphatase of the Greenland seal was purified to homogeneity, using immobilized concanavalin A. The specific activity of the enzyme is 1200-1500 mu/mg protein. The molecular mass of alkaline phosphatase as determined by electrophoresis performed under non-denaturating conditions is 260 kD, whereas that determined in the presence of beta-mercaptoethanol and SDS is 70 kD, which points to the tetrameric type of the seal alkaline phosphatase molecule. Using the atomic adsorption method, it was demonstrated that the phosphatase molecule contains four zinc atoms. Some physico-chemical parameters of seal alkaline phosphatase (pH-dependence, effects of temperature and cations on the enzyme activity, pI, thermal stability) were determined.     

Stabilization of human serum alkaline phosphatase to histidine-induced heat inactivation by tryptic digestion.

1. Serum alkaline phosphatase [EC 3.1.3.1] was strongly inactivated by histidine during incubation at pH 8.0 and 45degrees; however, tryptic digestion of the serum strongly protected the enzyme against inactivation by histidine. In the absence of histidine, however, neither heat inactivation of the phosphatase nor the effect of trypsin [EC 3.4.21.4] was observed. Factors affecting the alkaline phosphatase inactivation were studied further. 2. The effect of trypsin on the histidine-induced heat inactivation differed considerably according to the tissue source of the enzyme, which suggests a possible method for distinguishing alkaline phosphatase isoenzymes.     

Cloning and sequencing of bovine kidney alkaline phosphatase cDNA

The molecular cloning and nucleotide sequencing of bovine kidney alkaline phosphatase is reported. The homology with the human enzyme is about 90% at both the nucleotide and amino acid levels. The only significant sequence differences occur at the respective C termini. The high degree of homology also extends into the 5' and 3' untranslated regions of the two cDNAs.     

Purification and partial sequencing of bovine liver alkaline phosphatase

Bovine liver alkaline phosphatase has been purified to homogeneity by procedures that include reverse-phase HPLC. The pure enzyme has an apparent Mr of 160,000 and is composed of what appears to be two identical monomers of Mr 82,000. About 80% of the material yielded the amino-terminal sequence Leu-Val-Pro-Glu-Lys-Glu-Lys-Asp-Pro-?-Tyr-?-Arg-Asp-Gln-Ala-Gln. The minor component was extended at the amino terminus by two residues that have not yet been identified, i.e., ?-?-Leu-Val-Pro-Glu-Lys-Glu-Lys-Asp-Pro-?-Tyr-?-Arg-Asp-Gln-Ala-Gln.     

Ultrastructural localization of alkaline phosphatase activity in the intestine of developingRana Catesbeiana

Summary Alkaline phosphatase activity has been localized at the light and electron microscopic levels in the intestine of developing frog,Rana catesbeiana. The intensity of the histochemical reactivity decreases along the intestinal tract. The intracellular localization of the enzymatic activity shows continuous series of organelles loaded with the reaction product from the Golgi zones to the brush border. These results are in agreement with the biochemical observations made on the same material.This work was supported by grants from the France-Quebec agreements (J. Hourdry) and from the Medical Research Council of Canada (J.S. Hugon)     

Giardia lamblia: expression of alkaline phosphatase activity in infected rat intestine

Alkaline phosphatase (IAP) is a marker of intestinal microvillus membrane. Changes in IAP activity have been studied as a function of Giardia lamblia (G. lamblia) infection using rat as the experimental model. At day 11 and 15 post-infection, enzyme activity was reduced (p<0.01) compared to controls. The enzyme levels were essentially similar to control values by day 30 post-infection. Analysis of the enzyme activity in cell fractions across crypt-villus axis revealed a marked decrease in enzyme activity in the villus tip and mid villus regions but a considerable increase (p<0.01) in enzyme activity in the crypt base of 11 day post-infected animals compared to that in controls. The observed changes in IAP activity were confirmed by assaying the enzyme activity in acrylamide gels using bromo-chloro-indolyl phosphate staining under non-denaturing conditions. These findings indicate differential changes across the crypt-villus axis, but impaired alkaline phosphatase levels in G. lamblia infected rat intestine.     

The catalytic-centre activity and kinetic properties of bovine milk alkaline phosphatase

1. The phosphorylation of milk alkaline phosphatase was studied under various conditions: maximum incorporation occurred at pH5.0 and 50% incorporation at pH6.6-7.0. 2. The phosphorylation was shown to be specific and the results suggest that the active centre of the enzyme is involved in the process. 3. Phosphoryl-enzyme is rapidly hydrolysed at alkaline pH. at pH7.0 the results suggest that a phosphoryl-enzyme could occur as a transient intermediate in the hydrolysis of phosphate esters by the phosphatase. 4. The catalytic-centre activity of the enzyme was found to be 2700sec.(-1) at pH10.0 and 25 degrees with p-nitrophenyl phosphate as substrate.     

Purification and partial amino acid sequencing of bovine kidney alkaline phosphatase

Bovine kidney alkaline phosphatase (ALPase) was purified by the sequential application of monoclonal anti-bovine cartilage ALPase affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate-polyacrylamide-gel electrophoresis showed the presence of a single band corresponding to a molecular weight of 80,000. The N-terminal amino acid sequence of bovine kidney alkaline phosphatase was determined as follows: Leu-Val-Pro-Glu-Lys-Asp-Pro-?-Tyr-Trp-Arg-Asp-Gln-Ala-Gln.