Serum levels of intestinal alkaline phosphatase in type 2 diabetic patients with enteropathy

Background: Type 2 diabetes mellitus patients frequently have various distressing gastrointestinal signs and symptoms and intestinal alkaline phosphatase (IAP) may be linked to it. Even after extensive search, there was dearth of literature related to IAP levels in serum of diabetic enteropathy subjects. So, using a case-control design, levels of IAP in the serum of T2DM subjects were determined.Methods: Serum IAP was measured by ELISA in 73 type 2 diabetic patients with enteropathy (group 1) and 71 type 2 diabetic patients without enteropathy (group 2). Statistical analysis of the data was performed by using Statistical Package for Social Sciences (SPSS version 16) and inferences were drawn.Results: Serum IAP was highly significantly reduced in group 1 (3.9 U/L) compared to group 2 (4.2 U/L).Conclusions: Enteropathy in T2DM may be related to reduction in IAP levels in serum. Estimation of serum IAP may be considered in type 2 diabetic patients with enteropathy, for the elaboration of treatment strategy and monitoring.

Kinetic behaviour of calf intestinal alkaline phosphatase with pNPP.

The hydrolysis of p-nitrophenyl phosphate (pNPP) by calf intestinal alkaline phosphatase (CIAP) was investigated with respect to kinetic parameters such as Vmax, Km and Kcat under varying pH, buffers, substrate concentration, temperature and period of incubation. Highest activity was obtained with Tris-HCl at pH 11, while in the case of glycine-NaOH buffer the peak activity was recorded at pH 9.5. The enzyme showed the following kinetic characteristics with pNPP in 50 mM Tris-HCl at pH 11 and 100 mM glycine-NaOH at pH 9.5 at an incubation temperature of 37°C: Vmax, 3.12 and 1.6 µmoles min-1 unit-1; Km, 7.6 × 10-4 M and 4 × 10-4 M; and Kcat, 82.98 s-1 and 42.55 s-1, respectively. CIAP displayed a high temperature optimum of 45°C at pH 11. The kinetic behaviour of the enzyme under different parameters suggested that the enzyme might undergo subtle conformational changes in response to the buffers displaying unique characteristics. Bioprecipitation of Cu2+ from 50 ppm of CuCl2 solution was studied where 64.3% of precipitation was obtained. Pi generated from CIAP-mediated hydrolysis of pNPP was found to bind with copper and precipitated as copper-phosphate. Thus, CIAP could be used as a test candidate in bioremediation of heavy metals from industrial wastes through generation of metal-phosphate complexes.

Effect of gallic acid on alkaline phosphatase and peptidase activities in rat intestine.

Gallic acid is a normal constituent of many edible foods, thus directly interacts with epithelial tissue in intestine. In the present study, the effect of gallic acid on intestinal alkaline phosphatase (IAP) and peptidase activities in rat intestine was evaluated. Gallic acid (0.27-0.5 mM) inhibited activities of leucine aminopeptidase (LAP) and -glutamyl transpeptidase (-GTP) by over 90%, compared to controls in rat intestine. In contrast, 0.1-0.6 mM gallic acid either had no effect or stimulated the activity of IAP in rat intestine. The observed inhibition of peptidases by gallic acid was reversible in nature. Kinetic analysis revealed no change in Vmax of LAP (0.42-0.44 units/mg protein) and -GTP (0.22-0.24 units/mg protein), while the values of apparent Km were increased 6-7 fold, exhibiting competitive-type of enzyme inhibition by gallic acid. The values of Ki for LAP and -GTP were 0.037 mM and 0.017 mM, respectively. These observations indicate that gallic acid is a potent inhibitor of brush border peptidases, and thus may interfere in the digestion and absorption of proteins in the intestine.

Prevalence and Clinical Significance of Intestinal Alkaline Phosphatase in Healthy Adults / 대한진단검사의학회지

BACKGROUND: Intestinal alkaline phosphatase (ALP) is more prevalent in individuals of blood group B or O secretors and increases after a meal, especially, high-fat diet. The purpose of this study was to evaluate the prevalence and clinical significance of intestinal ALP in the sera of healthy adults. METHODS: Whole blood specimens were obtained from 42 healthy adults after fasting for at least 8 hours, and again at 2 hours after a regular meal. ALP was measured by TBA-200FR and analyzed for isoenzymes by Helena REP system. We also tested their ABO blood groups using GENEDIA anti-A and anti-B sera. RESULTS: The levels of fasting ALP, postprandial ALP, and the difference between the fasting and postprandial ALP (ALP difference) were 57.6+/-20.8 (12-111) IU/L, 62.3+/-17.4 (27-120) IU/L, and 4.6+/-15.4 (-8~63) IU/L, respectively. Delta (delta) ALP was 27.6+/-86.3 (-11.4~312.5)%. Among the 42 subjects, 6 were blood group A, 16 group B, 10 group AB, and 10 group O. Intestinal isoenzyme of ALP was detected in two subjects, both of whom were blood group O. The differences in fasting ALP, postprandial ALP, ALP difference, and delta ALP between ABO blood groups were statistically not significant. CONCLUSIONS: Intestinal ALP was detected in 5% of healthy adults, especially, in 20% of blood group O. Intestinal ALP has been known to be of no specific clinical significance. However, when ALP is measured in a non-fasting sample, the presence of intestinal ALP could result in an abnormally high ALP and subsequent unnecessary tests. Therefore, it is recommended that ALP should be measured only after fasting.