Phosphatases classification

The first evidence for a unique class of enzymes, transcending conventional phosphatase classification, came firom work on bovine spleen add phosphatase It was found that this phosphoprotein phosphatase was capable of removing the phosphorus from... 

Protein Phosphatases. Figure 3 Classification of protein tyrosine phosphatases. See text for details. Common names for selected PTPs are used according to Ref. [2]. 

A machine-learning method was proposed by Klon et al. [104] as an alternative form of consensus scoring. The method proved unsuccessful for PKB, but showed promise for the phosphatase PTPIB (protein tyrosine phosphatase IB). In this approach, compounds were first docked into the receptor and scored using conventional means. The top scoring compounds were then assumed to be active and used to build a naive Bayes classification model, all compounds were subsequently re-scored and ranked using the model. The method is heavily dependent upon predicting accurate binding... 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

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],... 

Phosphatases are numerous and important enzymes (see also Chapt. 2). They are classified as phosphoric monoester hydrolases (phosphatases, EC 3.1.3), phosphoric diester hydrolases (phosphodiesterases, EC 3.1.4), triphosphoric monoester hydrolases (EC 3.1.5), diphosphoric monoester hydrolases (pyrophosphatases, EC 3.1.7), and phosphoric triester hydrolases (EC 3.1.8) [21] [63]. Most of these enzymes have a narrow substrate specificity restricted to endogenous compounds. However, some of these enzymes are active toward xenobiotic organophosphorus compounds, e.g., alkaline phosphatase (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), aryldialkylphosphatase (para-oxonase (PON1), EC 3.1.8.1) and diisopropyl-fluorophosphatase (tabunase, somanase, EC 3.1.8.2) [64 - 70]. However, such a classification is far from definitive and will evolve with further biochemical findings. Thus, a good correlation has been found in human blood samples between somanase and sarinase activities on the one hand, and paraoxonase (PON1) type Q isozyme concentrations on the other [71]. 

The alkaline phosphatase activity under consideration is that of a monophosphohydrolase (International Enzyme Classification 3.1.3.1). 

It was possible, in the preceding section, to arrive at a biochemical classification in normal healthy subjects. The moieties measured are simply the alkaline phosphatase activity of unheated and heated serum in the presence of n- and L-phenylalanine, respectively. Depending on the individual s blood type, secretor status, and sex, the mean values and relative proportions of each may differ. 

Patankar, S.J. and Jurs, P.C. (2003b) Classification of inhibitors of protein tyrosine phosphatase IB using molecular structure based descriptors. 

Ingebritsen TS, Cohen P (1983) The protein phosphatases involved in cellular regulation. 1. Classification and substrate specificities. Eur J Biochem 132 255-261... 

ADP AFP ab as ALAT AP ASAT ATP BQ BSA CEH CK CME COD con A CV d D E E EC ECME EDTA EIA /e FAD FET FIA G GOD G6P-DH HBg HCG adenosine diphosphate a-fetoprotein antibody antigen alanine aminotranferase alkaline phosphatase aspartate aminotransferase adenosine triphosphate benzoquinone bovine serum albumin cholesterol ester hydrolase creatine kinase chemically modified electrode cholesterol oxidase concanavalin A coefficient of variation (relative standard deviation) layer thickness diffusion coefficient enzyme potential Enzyme Classification enzyme-chemically modified electrode ethylene diamine tetraacetic acid enzyme immunoassay enzyme loading factor flavin adenine dinucleotide field effect transistor flow injection analysis amplification factor glucose oxidase glucose-6-phosphate dehydrogenase hepatitis B surface antigen human chorionic gonadotropin... 

Reflecting the lack of in-depth experimental data available at this time, even the classiflcation of metal-dependent enzymes was notably nonsystematic. In an early review, five categories were set forth heme, copper-containing, proteolytic, carbonic anhydrase, and phosphatase . A later classification" was made according to the types of reactions catalyzed electron transfer or redox (Cu, Fe, Mo), group transfer (Mg, Mn), decarboxylations and hydrolyses (Mn, Zn), and binding of pyridine nucleotide cofactors (Zn). 

The introduction of a classification system for PP has been useful in characterization of the most abundant enzymatic forms from various tissues. However, cloning of cDNA for the PP catalytic subunits has led to the conclusion that PP is an expanding family, and other types of Ser/Thr phosphatases (PPX, PPZ, etc.) exist and are distinct from PPl and PP2 (Cohen and Cohen, 1989). Recognition of the dual specificity (Ser/Thr and Tyr) has been a significant development and the Tyr phosphatases also represent a new class (Guan et al., 1991). Thus the application of a rigid classification may not be appropriate and the use of a more flexible system may be imposed by future research. 

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