Serine Methyl Ester Research Articles

Ring—chain tautomerism of diastereomeric N-(2-furylidene)-β-(2-furyl)serine esters: a 1H and 13C NMR study of steric and solvent effects

1H and 13C NMR data indicate that in solution the erythro-form of N-(2-furylidene)-β-(2-furyl)serine methyl ester is in equilibrium with one cyclic tautomer of the oxazolidine type whereas the threo-form is in equilibrium with two. The dynamics of equilibration and the tautomeric distribution are discussed in terms of steric and solvent effects.

Synthesis of optically active amino ketones from (s)-serine

The oxazoline-protected (S)-serine methyl ester 2 can be coupled with various organolithio compounds to give the corresponding ketones 4a-d in good yield without racemisation.

Diphenylphosphino -α -aminosäureester als Liganden in Palladium(II)-und Platin(II)-Komplexen [1] / Diphenylphosphino-α-Amino Acid Esters as Ligands in Palladium(II) and Platinum(II) Complexes [1

Abstract cis-Dichlorobis(chlorodiphenylphosphine)palladium-and platinum(II) react with N-alkyl-α-amino acid esters to give the complexes MCl2[Ph2PN(R)C(H)(R')CO2Me]2 (M = Pd, Pt; R = CH2Ph, i-C3H7; R' = CH3, CH2Ph). With lysine ester dimeric, bis(chelate) complexes (M = Pd, Pt; R = CH3, C2H5) have been isolated. The reaction of cis-MCl2(PPh2Cl)2 with cysteine and serine methylester affords the complexes MCl2[Ph2P(X)CH2C(H)(NH2)CO2CH3]2 (M = Pd, Pt; X = O, S).

The synthesis of an ATP-γ-Peptidyl ester as a potential probe of c-AMP-dependent protein kinases

The synthesis of a γ-dipeptidyl ester of ATP has been effected by coupling a phosphopeptide (e.g. N-acetylalanyl-O-(phosphoryl)serine methyl ester) to ADP in the presence of 1,1′-carbonyldiimidazole. Compounds of this type, containing longer peptides, are proposed as potential multisubstrate adduct inhibitors of c-AMP-dependent protein kinases.

Oxidation of benzyloxycarbonyl threonine and serine methyl esters to an oxamate derivative

Both benzyloxycarbonyl threonine and serine methyl esters, when subjected to oxidation with reagents based on chromium (VI) oxide, gave rise to the same N -protected methyl oxamate, whose structure was confirmed by an independent preparation.

Motions and interactions of phospholipid head groups at the membrane surface. 3. Dynamic properties of amine-containing head groups.

The dynamic properties of the amine-containing head groups of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and a new phospholipid, phosphatidylserine methyl ester, were studied. Deuterium NMR spin-lattice (T1) relaxation times of deuterium labels specifically incorporated in the head groups were measured in multilamellar dispersions of these phospholipids. As a reference point, the data were compared with T1 values from a phospholipid with a simple phosphopropanol head group. In the liquid-crystalline state at both the alpha (P--O--CD2--CH) and beta (P--O--CH2--CD) head-group segments, the values of the T1 relaxation times decreased in the order propyl greater than choline greater than ethanolamine greater than serine = serine methyl ester. In the propyl and choline head groups, the beta-segment T1 values were longer than those of the alpha segment, indicating increasing flexibility as one progressed toward the free end of the head group. The ethanolamine and serine head groups had essentially identical T1 values at all positions. Phosphorus-31 NMR spin-lattice relaxation times were found to parallel the deuterium results for the neighboring alpha segment. These data indicate that the phosphatidylserine head group is less flexible than that of phosphatidylethanolamine which in turn was more rigid than the phosphatidylcholine head group. The phosphatidylserine head-group T1 values were as short as those of the glycerol backbone moiety of phosphatidylcholine which is known to be a relatively rigid section of the phospholipid molecule. The relaxation time data for liquid-crystalline phase phosphatidylserine and gel phase phosphatidylglycerol were quantitatively similar, indicating that for those motions which contribute to T1 relaxation, the two head groups are in similar states. These differences in head-group rigidity are discussed in terms of the capacity of the various head groups to bind noncovalently to their neighbors in the plane of the membrane surface.

The structure and mechanism of stem bromelain. Evaluation of the homogeneity of purified stem bromelain, determination of the molecular weight and kinetic analysis of the bromelain-catalysed hydrolysis of N-benzyloxycarbonyl-L-phenylalanyl-L-serine methyl ester.

1. Purified stem bromelain (EC 3.4.22.4) was eluted from Sephadex G-100 as a single peak. The specific activity across the elution peak was approximately constant towards p-nitrophenyl hippurate but increased with elution volume with N(2)-benzoyl-l-arginine ethyl ester as substrate. 2. The apparent molecular weight, determined by elution analysis on Sephadex G-100, is 22500+/-1500, an anomalously low value. 3. Purified stem bromelain was eluted from CM-cellulose CM-32 as a single peak and behaved as a single species during column electrophoresis on Sephadex G-100. 4. Purified stem bromelain migrates as a single band during polyacrylamide-gel electrophoresis under a wide variety of conditions. 5. The molecular weight determined by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate is 28500+/-1000. 6. Sedimentation-velocity and equilibrium-ultracentrifugation experiments, under a variety of conditions, indicate that bromelain is an apparently homogeneous single peptide chain of mol.wt. 28400+/-1400. 7. The N-terminal amino acid composition is 0.64+/-0.04mol of valine and 0.36+/-0.04mol of alanine per mol of enzyme of mol.wt. 28500. (The amino acid recovery of the cyanate N-terminal amino acid analysis was standardized by inclusion of carbamoyl-norleucine at the cyclization stage.) 8. The pH-dependence of the Michaelis parameters of the bromelain-catalysed hydrolysis of N-benzyloxycarbonyl-l-phenylalanyl-l-serine methyl ester was determined. 9. The magnitude and pH-dependence of the Michaelis parameters have been interpreted in terms of the mechanism of the enzyme. 10. The enzyme is able to bind N-benzyloxycarbonyl-l-phenylalanyl-l-serine methyl ester relatively strongly but seems unable to make use of the binding energy to promote catalysis.

Carboxyl group modification and amide assignments in automated sequencing of proteins

A procedure is described for locating the amidated and non-amidated residues in automated sequence analysis of proteins. The method requires no additional identification procedure beyond hydrolysis of the thiazolinone derivatives followed by amino acid analysis. The free carboxyl groups of ribonuclease A were coupled with serine methyl ester or glycine ethyl ester in the presence of a water soluble carbodiimide. The derivatized proteins were then subjected to automated Edman degradation in the protein sequenator. At positions where the residue in the native protein was aspartic or glutamic acid, the coupled amino acid was recovered in addition to aspartic acid or glutamic acid after hydrolysis of the thiazolinone derivatives.

New Method to Prepare N-t -Butoxycarbonyl Derivatives and the Corresponding Sulfur Analogs from di- t -Butyl Dicarbonate or di- t -Butyl Dithiol Dicarbonates and Amino Acids

Di-t-butyl dicarbonate and one of its dithiol analogs, practical methods of preparation for which are given, react with amino-acid esters to form the N-t-butoxycarbonyl (t-BOC) derivatives and the thiol analogs in good yield under mild conditions. The thiol analogs are stable to acidic conditions, which rapidly remove the t-BOC group itself. t-Butyl trimethylsilyl carbonate forms a (CH(3))(3)Si ether from a N-thiol-t-BOC serine methyl ester. The N-thiol-t-BOC group can be removed from the -NHCOSR (R = t-butyl) by heating with peroxide-acetic acid.Action of the dicarbonates described above has not been attended by racemization in the cases examined. The two dicarbonates may be useful as agents for selective blocking and deblocking of amino or other groups.

Mass spectrometry of glycoproteins: O-glycosyl derivatives of L-serine and L-threonine

The mass spectra of acetylated O-glycosyl derivatives of serine and threonine methyl esters show characteristic features which allow identification of the amino acid and sugar moieties and the type of linkage between them. Some information concerning the sequence of sugar units and the position of the glycosidic bond in the carbohydrate moiety of disaccharide O-glycosyl derivatives of serine methyl ester is provided also by mass spectrometry.

A spectrophotometric method for the microdetermination of periodate.

1. A method is described for measuring the concentration of periodate over the range 0.2-20mum by adding 1,2-di-(p-dimethylaminophenyl)ethane-1,2-diol to a sample solution. Periodate cleaves this compound to from two molecules of p-dimethylaminobenzaldehyde, the extinction of which is then read at 352mmu. 2. The method has been used to follow the course of periodate oxidations of serine methyl ester, ribonuclease A and ribonuclease S-protein. Addition of the reagent stops further periodate reaction by reducing the remaining periodate to iodate. 3. The presence of protein does not interfere with the assay.

Copper(II), Nickel and Uranyl Complexes of Some Amino Acids1

The formation constants of copper(II) and nickel complexes of hydroxyproline, asparagine and N,Ndimethylglycine have been obtained. The pK2 of asparagine and the formation constants of its complexes are independeut of the optical configanration. The nickel complexes of serine methyl ester and glycine methyl ester are equally stable, indicating that the serine ester coordinates to the metal ion through the amino group only. At pH 1.90, uranyl ion forms a 1: 1 complex with glycine. In the pH region 3.0 to 4.3, the uranyl ion does not complex with glycine, hydroxyproline, asparagine, N,N- dimethylglycine and serine; only hydrolysis of the uranyl ion occurs.

A SYNTHESIS OF SERINE AND ITS METHYL ESTER

A SYNTHESIS OF SERINE AND ITS METHYL ESTER