Synthesis Of Dipeptides Research Articles

Solid-phase peptide synthesis by ion-paired alpha-chymotrypsin in nonaqueous media.

Solid-phase synthesis of dipeptides in low-water media was achieved using AOT ion-paired alpha-chymotrypsin solubilized in organic solvents. Multiple solvents and systematic variation of water activity, a(w), were used to examine the rate of coupling between N-alpha-benzyloxycarbonyl-L-phenylalanine methyl ester (Z-Phe-OMe) and leucine as a function of the reaction medium for both solid-phase and solution-phase reactions. In solution, the observed maximum reaction rate in a given solvent generally correlated with measures of hydrophobicity such as the log of the 1-octanol/water partitioning coefficient (log P) and the Hildebrand solubility parameter. The maximum rate for solution-phase synthesis (13 mmol/h g-enzyme) was obtained in a 90/10 (v/v) isooctane/tetrahydrofuran solvent mixture at an a(w) of 0.30. For the synthesis of dipeptides from solid-phase leucine residues, the highest synthetic rates (0.14-1.3 mmol/h g-enzyme) were confined to solvent environments that fell inside abruptly defined regions of solvent parameter space (e.g., log P > 2.3 and normalized electron acceptance index <0.13). The maximum rate for solid-phase synthesis was obtained in a 90/10 (v/v) isooctane/tetrahydrofuran solvent mixture at an a(w) of 0.14. In 90/10 and 70/30 (v/v) isooctane/tetrahydrofuran environments with a(w) set to 0.14, seven different N-protected dipeptides were synthesized on commercially available Tentagel support with yields of 74-98% in 24 h.

A Novel One‐Step Approach for the Preparation of α‐Amino Acids, α‐Amino Amides, and Dipeptides from Azetidine‐2,3‐diones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Lipase-Catalyzed Synthesis of Precursor Dipeptides of RGD in Aqueous Water-Miscible Organic Solvents

PPL-catalyzed synthesis of the precursor dipeptides of RGD as a cellular adhesion factor, Benzyl-Arg-Gly-NH2 and CBZ-Gly-Asp-NH2, was conducted in water-organic cosolvents systems. Five water-miscible organic solvents, which have some advantage over the water-immiscible organic solvent systems or the anhydrous organic solvent systems used often in protease-catalyzed synthesis of a peptide bond, were tested. The reaction condition of PPL-catalyzed synthesis of the dipeptides was optimized by examining the main factors affecting the product yield. The optimal reaction condition for the synthesis of Benzyl-Arg-Gly-NH2 was set up as pH 8.0, 15°C in 40% MeOH for 10 h with the maximum yield of 73.6%. The optimum condition for the synthesis of CBZ-Gly-Asp-NH2 was pH 7.0, 15°C in 50% MeOH for 10 h with the maximum yield of 67.0%.

Enzymatic Dipeptide Synthesis by Surfactant‐Coated α‐Chymotrypsin Complexes in Supercritical Carbon Dioxide

Enzymatic dipeptide synthesis by surfactant-coated alpha-chymotrypsin complexes was performed in supercritical CO(2) and liquid CO(2) at 308.2 and 333.2 K at pressures of 6.1 and 10.1 MPa. The enzymatic activity of coated alpha-chymotrypsin complexes for dipeptides synthesis at 10.1 MPa in supercritical CO(2) (SC-CO(2)) was higher than that in a liquid CO(2) and ethyl acetate solution at 6.1 MPa. The behavior of alpha-chymotrypsin in SC-CO(2) was similar to that in liquid ethyl acetate. And increasing the pressure and temperature increased the maximum conversion and the enzymatic reaction rate in SC-CO(2). Furthermore, the control of the water content in the reaction media had a dominant effect on the enzymatic activity. The maximum conversion for the dipeptide synthesis by the surfactant-coated alpha-chymotrypsin was obtained at 4% water content. The alpha-chymotrypsin complexes exhibited a higher enzymatic activity than native alpha-chymotrypsin in SC-CO(2). The nonionic surfactants l-glutamic acid dialkyl ester ribitol amide and sorbitan monostearate were more favored than the anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate.

Fmoc‐Amino Acid Azides in Peptide Synthesis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel one-step approach for the preparation of alpha-amino acids, alpha-amino amides, and dipeptides from azetidine-2,3-diones.

A remarkable reaction of azetidine-2,3-diones with primary as well as secondary amines, and water is presented. Simply by varying the nucleophile, an unprecedented one-step synthesis of alpha-amino acids, alpha-amino amides, and dipeptides, was developed in both the racemic and optically pure forms. The current mechanistic hypothesis invokes a concerted process involving CO extrusion. However, a stepwise pathway can also account for these novel transformations.

Bacillus licheniformis protease-catalyzed peptide synthesisvia the kinetically controlled approach using the carbamoylmethyl ester as an acyl donor in anhydrous acetonitrile

The couplings of N-protected amino acid esters with amino acid amides proved to be carried out in anhydrous acetonitrile in the presence of Bacillus licheniformis protease (subtilisin Carlsberg) immobilized on Celite. The maximal peptide yields were obtained with the immobilized enzyme prepared through lyophilization from a pH 10.7 buffer solution. A series of dipeptide syntheses and several segment condensations were achieved generally in high yields by the combined use of the immobilized enzyme prepared from this pH and the carbamoylmethyl ester as the acyl donor.

A Selected Ribozyme Catalyzing Diverse Dipeptide Synthesis

The sequence of events by which protein, RNA, and DNA emerged during early biological evolution is one of the most profound questions regarding the origin of life. The contemporary role of aminoacyl-adenylates as intermediates in both ribosomal and nonribosomal peptide synthesis suggests that they may have served as substrates for uncoded peptide synthesis during early evolution. We report a highly active peptidyl transferase ribozyme family, isolated by in vitro selection, that efficiently catalyzes dipeptide synthesis by using an aminoacyl-adenylate substrate. It was characterized by sequence and structural analysis and kinetic studies. Remarkably, the ribozyme catalyzed the formation of 30 different dipeptides, the majority of rates being within 5-fold that of the Met-Phe dipeptide required by the selection. The isolation of this synthetic ribozyme fosters speculation that ribozyme-mediated uncoded peptide synthesis may have preceded coded peptide synthesis.

ChemInform Abstract: L‐Selective Dipeptide Synthesis Using Novel Thermophilic Enzyme from Clostridium sp.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Design and synthesis of N-nonpolar nucleobase dipeptides: application of the Ugi reaction for the preparation of dipeptides having fluoroarylalkyl groups appended to the nitrogen atom

A single-step one-pot synthesis based on the Ugi four-component condensation of previously unknown dipeptides, 2, 3, 4 and 5, having a fluoroaromatic group appended to the nitrogen atom, is described. The series of dipeptides produced here can be viewed as nonpolar nucleobase dipeptides since the difluorotoluene nucleoside 1 is a well known nonpolar analogue of natural thymidine. A mixture of N-protected amino acids 7, fluorophenethylamines 6, isocyanides 8, and acetone or paraformaldehyde are stirred in methanol in the presence of 3 A molecular sieves to furnish the N-fluoroarylethyl-Aib- or -Gly-containing dipeptides 2 or 3, in moderate yields. The dipeptides 2d and 3b, having a cyclohex-1-enamide moiety, are deprotected readily with 3 M HCl in THF to afford the free dipeptides in high yields. The N-fluoroarylmethyl-Aib- or -Gly-containing β-alanyl dipeptides 4 or 5, designed based on the structure of 2′,5′-linked isoDNA, are also synthesized in a similar fashion to the preparation of 2, in moderate to good yields as both protected and free dipeptides.

L-Selective dipeptide synthesis using novel thermophilic enzyme from Clostridium sp.

A novel, inexpensive, thermophilic protease-type enzyme isolated from Clostridium thermohydrosulfuricum was used for dipeptide synthesis. The enzyme showed broad substrate selectivity and enantioselectivity towards l-amino acids in peptide bond formation.

Formation of Peptides at Half-Sandwich Complexes Using β- and γ-Amino Acid Esters and a Facile Dipeptide Synthesis from an N,O-Glycinato Half Sandwich Complex [RuCl(NH2CH2CO2)(η6-C6Me6)

The tripeptide ester complexes 2 and 3 are obtained from the diglycine ester complex [RuCl(N,N′-glyglyOMe-H+)(η6-C6Me6)] and the amino acid esters H2N(CH2)nCO2Me (n = 2, 3). The reaction of the N,O-glycinato complex [RuCl(NH2CH2CO2)(η6-C6Me6)] with the β-, γ- and δ-amino acid methyl esters H2N(CH2)nCO2Me (n = 2,3,4) in CH3OH and in the presence of NaOMe affords the η3-N,N′O-dipeptide complexes [Ru{H2N(CH2)nCONCH2CO2}(η6-C6Me6)] 5−7 in good yields. These complexes are also obtained in a one pot reaction from [RuCl(μ-Cl)(η6-C6Me6)]2, glycine and the amino acid ester. The formation of small peptides at the metal represents a facile procedure which does not require either a protecting/activating group or a coupling agent.

Formation of Peptides at Half-Sandwich Complexes Using β- and γ-Amino Acid Esters and a Facile Dipeptide Synthesis from anN,O-Glycinato Half Sandwich Complex [RuCl(NH2CH2CO2)(η6-C6Me6)

The tripeptide ester complexes 2 and 3 are obtained from the diglycine ester complex [RuCl(N,N′-glyglyOMe-H+)(η6-C6Me6)] and the amino acid esters H2N(CH2)nCO2Me (n = 2, 3). The reaction of the N,O-glycinato complex [RuCl(NH2CH2CO2)(η6-C6Me6)] with the β-, γ- and δ-amino acid methyl esters H2N(CH2)nCO2Me (n = 2,3,4) in CH3OH and in the presence of NaOMe affords the η3-N,N′O-dipeptide complexes [Ru{H2N(CH2)nCONCH2CO2}(η6-C6Me6)] 5−7 in good yields. These complexes are also obtained in a one pot reaction from [RuCl(μ-Cl)(η6-C6Me6)]2, glycine and the amino acid ester. The formation of small peptides at the metal represents a facile procedure which does not require either a protecting/activating group or a coupling agent.

ChemInform Abstract: An Efficient Approach to Asymmetric Synthesis of Dipeptide β‐Turn Mimetics: Indolizidinone Amino Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Microwave-enhanced solution coupling of the α,α-dialkyl amino acid, Aib

The difficult coupling of α-aminoisobutyric acid (Aib), during the synthesis of dipeptides ( 1– 6 ), was carried out using PyBOP/HOBt and HBTU/HOBt reagents by application of microwave energy in the presence of solvent. Room temperature, conventional heating (oil bath) and microwave irradiation of the reactions are compared. Synthesis by microwave irradiation gave the desired compounds in higher yields and in shorter reaction times than those obtained by conventional heating or at room temperature.

Novel kinetic analysis of enzymatic dipeptide synthesis: effect of pH and substrates on thermolysin catalysis.

The point of maximum activity is specific to a particular substrate-enzyme system but may vary with different substrates and the same enzyme. The specificity of enzymes has, however, been generally reported only at their "optimal" pH. In this article, we introduce the Michaelis-Menten equation taking pH into account, and apply it to the pH-activity profile of the thermolysin-catalyzed dipeptide synthesis. It has been reported to date that the pH-activity profile of thermolysin follows a bell-shaped curve with a maximal activity at or near pH 7.0. The profiles obtained in this study, however, indicated that the optimal pH varied from 5.8 (for F-AspPheOMe) to 7.3 (for Z-ArgPheOMe), and the order of thermolysin activity was greatly dependent on the pH of reaction media. We have succeeded in evaluating the substrates-induced change of the dissociation states of the active site of thermolysin using the hydrophobicity of substrates. We have obtained apparent kinetic parameters which are independent of the pH of reaction media. The apparent specificity of thermolysin which were independent of pH of the reaction media was in order L-Leu > L-Asp > L-Arg > L-Ala > L-Gly > L-Val and Z > Boc = F at P1 and P2 positions, respectively.

Dipeptide synthesis by an isolated adenylate-forming domain of non-ribosomal peptide synthetases (NRPS)

A deletion mutant of tyrocidine synthetase 1 (ΔΔTY1), comprising the adenylation domain of TY1 as an independent functional adenylate-forming unit, was used to investigate the ability of the adenylation domain in non-ribosomal peptide synthetases to catalyse peptide bond formation from the aminoacyl adenylate intermediate. The results demonstrate that only one substrate amino acid needs to be activated as an aminoacyl adenylate. In view of the potential exploitation of peptide synthetases for enzymatic synthesis of dipeptides of choice, it is important to note that this does not necessarily require a dimodular construct or an intermediate acyl transfer step.

Synthesis of phosphonamide and thiophosphonamide dipeptides.

Synthesis of phosphonamide and thiophosphonamide dipeptides.

Highly concentrated water-in-oil emulsions as novel reaction media for protease-catalysed kinetically controlled peptide synthesis

High-internal-phase-ratio-emulsions (HIPREs) or gel emulsions, formulated with a large amount of water (80.0–99.5% w/w), were investigated as reaction media for α-chymotrypsin-catalysed peptide synthesis under kinetic control using Ac-L-Phe-OEt and H-L-Leu-NH2 as model substrates. Both the initial reaction rate and dipeptide yield were examined as a function of the structure of the non-ionic polyoxyethylene alkyl ether type surfactant, alkyl chain length of the oil component, temperature and aqueous buffer content. Dipeptide yields of 70% were achieved in gel emulsions formulated with 90% w/w aqueous buffer. In these systems, the reaction performance was found to be independent of the gel emulsion system (i.e. surfactant and oil) and therefore of the water–oil interfacial tension. Interestingly, α-chymotrypsin showed superactivity at surfactant concentrations ranging between 0.2 and 0.8% w/w, that is, at 99.5 and 98.0% w/w water content, respectively. Furthermore, high dipeptide yields (90–94%) were achieved in the gel emulsions studied at very high substrate concentrations and thus with undissolved reactants. Under these conditions, examples of α-chymotrypsin-catalysed dipeptide synthesis on an analytical and preparative scale were conducted.

Di-tert-butyl Dicarbonate (Boc-anhydride, Boc2O)

The multifarious role of di-tert-butyl dicarbonate (Boc-anhydride, Boc2O) as protecting group, isocyanating agent, activator of carboxylic acid, lactonisation agent and as a dehydrating agent has been well documented in the records of literature. It is also an efficient tert-butoxycarbonylating agent for alcohols, thiols, amines and carbon nucleophiles. From our group, it has also been exploited as a cyclodehydrating agent for N-acylamino acids forming oxazoles and benzoxazinones and as a novel reagent for an efficient synthesis of dipeptides under mild, non-racemizing conditions. It’s inexpensive, easy to introduce and cleave as a protecting group, gives innocuous by-products t-BuOH and CO2, and it’s mild, and high yielding reaction procedures all add to its value as a versatile and eco-friendly reagent.