3-Phosphoserine

Aminoadipic acid y-Carboxyglutamic acid Pyroglutatnic acid Phosphoserine Phospho threonine Phospho tyrosine... 

Protein phosphatases are classified according to their activity toward phospho-amino acids they act on (Fig. 1). Nomenclature is independent of regulation simply because stimuli were unknown. Protein phosphatases hydrolyzing O-phospho-monoesters are currently subdivided into two major classes (i) phosphatases acting on phosphoserine (pSer) and phosphothreonine (pThr), and (ii) the second class... 

Die l4-3-3s are a family of 30 kDa proteins that exist as homo- and heterodimers within all eukaryotic cells. 14-3-3 proteins bind target proteins containing phospho-threonine or phosphoserine motifs, however exceptions do exist. Die docking of 14-3-3s to their target can ... 

The aminoalkanephosphonic acids which bear an additional hydroxy group in the molecule were usually resolved via enzymatic acylation of this hydroxy group. For example, resolution of //-Cbz-phosphoserine dimethyl ester 60 using various lipases gave poor results. However, lipase PS-promoted acetylation of //-Chz-phosphoisoserine diethyl ester 61 gave both the unreacted substrate 61 and the 0-acetylated product 62 with almost 100% enantiomeric excess (E = 1000). ... 

As an alternative process, the nitrone (138 R Cl OCl Ph) yields a mixture of diastereoisomeric (benzyloxymethyl)phosphonic derivatives of which (141) is the main component acidolysis and hydrogenolytic debenzylation lead to phosphoserine (143), the (S) chirality of which was demonstrated by )(-ray analysis of the derivative (144). In a further variation, the di-tert-butyl... 

The endothelin B receptor is an example of characterization of a homogeneous, affinity purified protein (Roos et al., 1998). Significant progress has been made in the development of techniques for more high-throughput identification of phosphorlyation events. Analysis of large sets of phosphorylated proteins is facilitated by the availability of affinity purification methods such as anti-phosphotyrosine or anti-phosphoserine antibodies or metal affinity chromatography (Neubauer and Mann, 1999 Soskic et al., 1999). These methods are not specific to a particular protein but rather are used to fractionate all proteins that are phosphorylated. 

The second method also relies on site-specific chemical modification ofphosphoproteins (Oda et al., 2001). It involves the chemical replacement of phosphates on serine and threonine residues with a biotin affinity tag (Fig. 2.7B). The replacement reaction takes advantage of the fact that the phosphate moiety on phosphoserine and phosphothreonine undergoes -elimination under alkaline conditions to form a group that reacts with nucleophiles such as ethanedithiol. The resulting free sulfydryls can then be coupled to biotin to create the affinity tag (Oda et al., 2001). The biotin tag is used to purify the proteins subsequent to proteolytic digestion. The biotinylated peptides are isolated by an additional affinity purification step and are then analyzed by mass spectrometry (Oda et al., 2001). This method was also tested with phosphorylated (Teasein and shown to efficiently enrich phosphopeptides. In addition, the method was used on a crude protein lysate from yeast and phosphorylated ovalbumin was detected. Thus, as with the method of Zhou et al. (2001), additional fractionation steps will be required to detect low abundance phosphoproteins. 

Figure 9.2. Chromatogram of a seawater extract (20 ml) sample for amino acids collected at 6 m in the Kiel Fjord. The concentrations of the individual acids were quantified as follows (in nmol/1) meto, 11 asp 34.4 thr, 23.2 ser, 88 glu, 36 gly, 100 ala, 56 vol, 16 ileu, 9.6 leu, 12 galactosamine and amino sugars, 4 tyr, 6.8 phe, 7.2 B-ala, 20.8 a-amino-y, 14.4 orn, 44 lys, 12 hist, 7.2 arg, 8.6 cysS02H, 4 cit, trace tan, cys, trace glucose-amine, trace met, trace urea, trace phosphoserine, trace OH-lys, trace. The total concentration of amino acid in the sample lies around 51 q.g/1, assuming a mean molecular weight of 100. Source [264]...

The phosphotyrosine-recognition subdomain confers substrate specificity of PTPs by creating a deep pocket (9 A) so that only the phosphotyrosine moiety is long enough to reach the cysteine nucleophile located at the base of this pocket phosphoserine and phosphothreonine... 

The hydration behavior of DPPS (Tc = 55 °C) LB films is shown in Figure 13. The DPPS LB film having phosphoserine head groups little hydrated (Am = 600 10 ng, 20 mol of water per lipid) even near the phase transition temperature. Hydration ability has been reported from adsorption experiments of water vapor to lipid powder to be in the order of PC > PE > PS lipids [43], It has been determined from calorimetry that the amount of non-frozen water around lipid molecules is 10 mol, 7-8 mol, and 0 mol for 1 mol of PC, PE, and PS lipids, respectively [44]. This tendency is consistent with our results that PC molecules are easily hydrated and flaked from the substrate, and PE and... 

Figure 10.9 Active site of Methanococcus phosphoserine phosphatase with Mg2+ and phosphoserine in the active site (a) and of human phosphoserine phosphatase with Ca2+ bound and the modelled substrate in the active site (b). (From Peeraer et al., 2004. Reproduced with permission of Blackwell Publishing Ltd.)...

Peeraer, Y., Rabijns, A., Collet, J.-F., Van Scafdngen, E. and De Ranter, C. (2004) How calcium inhibits the magnesium-dependent enzyme human phosphoserine phosphatase, Eur. J. Biochem., 271, 3421-3427. 

This should be illustrated by the counterion concentration dependencies of three different model solutes, namely Af-3,5-dinitrobenzoylated serine (DNB-Ser), aspartic acid (DNB-Asp), and O-phosphoserine (DNB-PSer), which are structural analogs that differ in the number of nominal charges. The solutes have been analyzed in the RP mode with methanol-phosphate buffer (50 50 v/v) (pH 6.5) under variable phosphate concentrations. The results are shown in Figure 1.4. 

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