L-Phenylalanine inhibition of human alkaline phosphatases with p-nitrophenyl phosphate as substrate.

Abstract

With p-nitrophenyl phosphate as the substrate, there reportedly is no organ-specific inhibition of alkaline phosphatase (EC 3.1.3.1) activity by L-phenylalanine. However, we found that at pH 10.0, with p-nitrophenyl phosphate as the substrate, L-phenylalanine obviously inhibits the alkaline phosphatase isoenzyme from human placenta, whereas there is little if any inhibition of the isoenzyme from human intestine. Because of the differing effects of substrates (p-nitrophenyl phosphate and phenyl phosphate) and their enzymic products (p-nitrophenol and phenol) for L-phenylalanine action on the placental alkaline phosphatase isoenzyme, we suggest that the isoenzyme--inhibitor--substrate complex and the effect of released phosphate on L-phenylalanine inhibition of the isoenzyme activity differ from each other.

Kinetic Studies for the Inhibition Effect of Pentachlorophenol on Alkaline Phosphatase Activity <i>In Vitro</i>

“…This indicates that the inhibition of bovine intestinal mucosa ALP by PCP is of an uncompetitive type, which means that the PCP could bind to the enzyme-substrate (ES) complex and caused a reduction of ALP activity. In the present study, the K m value, which depends on the catalytic reaction conditions and the type of substrate, for bovine intestinal mucosa ALP with p-NPP as substrate was found to be near to the value for bone ALP with β-naphthyl phosphate (0.110 -0.118 mM) [18] and the value for intestinal ALP with p-nitrophenyl phosphate (0.1 mM) as substrate [19]. Uncompetitive inhibition of bovine intestinal mucosa ALP by PCP was similar to uncompetitive inhibition of Escherichia coli ALP by L-phenylalanine [13] and human placental and germ-cell ALP by L-Leu and L-Phe [14].…”

Bone alkaline phosphatase measured with a new immunoradiometric assay in patients with metabolic bone diseases

“…In order to improve the sensitivity and the specificity of the information provided by the measurement of T-ALP, several techniques have been developed to differentiate bone from liver isoenzymes. Traditional methods for fractionating and quantifying B-ALP are based upon biochemical differences between the isoenzymes such as heat inactivation [13], inhibition by amino acids and urea [14], wheat germ lectin precipitation [15] and agarose gel electrophoresis [16,17]. However, all these techniques have proved to be technically cumbersome, not always specific and not well suited for routine measurements.…”

Supramolecular Approach to Enzyme Sensing on Paper Discs Using Lanthanide Photoluminescence

“…As a result, paper based colorimetric, − electrochemical, chemiluminescent, electrochemiluminescent, , and fluorescent − sensors have found uses in sensing ions, , glucose, , H 2 O 2 , − DNA, and biomarkers. ,, Enzymes are important target bioanalytes in the field of biosensors as they play crucial roles in the regulation of metabolic functions in living systems. − The detection of enzyme activity through an efficient and simple design is therefore of utmost importance. The most commonly employed enzyme assays are solution based and the detection is done either through colorimetry − or through fluorimetry. , Although the fluorescence based assays provide a higher intrinsic sensitivity, the autofluorescence from biological samples interferes with the measurements and this is a drawback for the detection of bioanalytes. In this context, a paper based sensing platform to detect enzyme activity through a delayed luminescence read-out would be more convenient.…”