A novel compound, diethyl puerarin-7-yl phosphate, was synthesized through a simplified Atheron-Todd reaction for the first time. The structure of this compound was elucidated by IR, ESI-MS and NMR. Two conformations ...A novel compound, diethyl puerarin-7-yl phosphate, was synthesized through a simplified Atheron-Todd reaction for the first time. The structure of this compound was elucidated by IR, ESI-MS and NMR. Two conformations of the compound were testified by 2D NMR (HSQC and HMBC) and dynamic NMR. Furthermore, we carried out the conformational analysis using chemical calculation by the Gaussian 03. Finally, we obtained two preferred conformations and energy values.展开更多
The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by the...The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.展开更多
5,7-Dimethoxy-2-phenylquinolin-4-yl phenyloxy (N-L-alanine ethyl ester) phosphoramidate (C28H29N2O7P, Mr = 536.17) has been synthesized by a facial phosphorylated reaction, and its structure was determined by IR, ...5,7-Dimethoxy-2-phenylquinolin-4-yl phenyloxy (N-L-alanine ethyl ester) phosphoramidate (C28H29N2O7P, Mr = 536.17) has been synthesized by a facial phosphorylated reaction, and its structure was determined by IR, NMR, HR MS and X-ray single-crystal diffraction. The crystal belongs to triclinic, space group P1^-, with a = 11.375(2), b = 11.591(2), c = 11.638(2) A^°, α= 109.46(3), β= 104.58(3), γ= 100.48(3)°, V = 1339.6(5)A^°^3, Z = 2, Dc = 1.330 g/cm^3,μ = 0.152 mm^-1, F(000) = 564, the final R = 0.0654 and wR = 0.1546. In the crystal structure, the title compound is constructed by a centrosymmetric dimmer unit composed of a pair of π-π stacking diastereoisomers. The compound has a noteworthy feature in the framework, and such units are linked by two equal intermolecular P=O…H-N hydrogen bonds.展开更多
Highly regioselective homocoupling of N,N-dialkylanilines can be achieved in water with cerium reagents, in which various N,N,N′,N′-tetraalkylbenzidines are obtained from N,N-dialkylanilines either by direct oxidati...Highly regioselective homocoupling of N,N-dialkylanilines can be achieved in water with cerium reagents, in which various N,N,N′,N′-tetraalkylbenzidines are obtained from N,N-dialkylanilines either by direct oxidation by cerium(Ⅳ)reagents or by cerium(Ⅲ) reagents in the presence of hydroperoxide.展开更多
In this paper, we described an improved electrochemical method for synthesis of some 1-aryl-2-pyrrolidinecarbonitrile derivatives bearing an electron-withdrawing group (NO2). The electrochemical synthesis of titile ...In this paper, we described an improved electrochemical method for synthesis of some 1-aryl-2-pyrrolidinecarbonitrile derivatives bearing an electron-withdrawing group (NO2). The electrochemical synthesis of titile compounds has been successfully performed in an undivided cell in reasonable yields.展开更多
The crystal of the title compound, [Ni(C15HgBr2ClNO2)(C18H15P)(C10H7)](C18H15P), has been prepared and confirmed by X-ray diffraction. The crystal belongs to the triclinic system, space group PI with a = 9.991...The crystal of the title compound, [Ni(C15HgBr2ClNO2)(C18H15P)(C10H7)](C18H15P), has been prepared and confirmed by X-ray diffraction. The crystal belongs to the triclinic system, space group PI with a = 9.991(3), b = 15.250(4), c = 18.542(5) A, α = 104.927(5), β = 104.009(6), γ = 94.422(6)°, V= 2619.2(11)A^3, Z = 2, Mr = 1140.91, Dc= 1.447 g/cm^3, F(000) = 1160 and μ(MoKα) = 2.053 mm^-1. The structure is refined to R = 0.0779 for 3773 observed reflections with I 〉 2σ(I) and wR = 0.1694 for 9026 unique reflections. The crystal (1-PPh3) is composed of neutral nickel(Ⅱ) complexes and co-crystallized PPh3 molecules. Intramolecular C-H...π interactions between C-H bond of the aldehyde group and phenyl ring of the coordinated PPh3 molecule in the nickel(Ⅱ) complex are observed, and intermolecular π-π interactions between neutral nickel(Ⅱ) complexes are also found in the crystal.展开更多
Different hydroxy substituted coumarins were successfully phosphorylated with diisopropylphophite (DIPPH) by the Atherton-Todd reaction in 76-89% yields. Moreover, the reaction activities of different hydroxys of th...Different hydroxy substituted coumarins were successfully phosphorylated with diisopropylphophite (DIPPH) by the Atherton-Todd reaction in 76-89% yields. Moreover, the reaction activities of different hydroxys of the coumarins in the Atherton-Todd reaction were studied.展开更多
Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation...Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.展开更多
Newlase F is a rude enzyme which contains triacylglycerol lipase and acid protease. Hydrolysis of dipeptide heptyl esters with Newlase F was studied in phosphate buffer-organic solvent by HPLC. When the Newlase F'...Newlase F is a rude enzyme which contains triacylglycerol lipase and acid protease. Hydrolysis of dipeptide heptyl esters with Newlase F was studied in phosphate buffer-organic solvent by HPLC. When the Newlase F's level reached 5 mg/mL under mild condition (PH 7.0, 30 degreesC), the lipase had the highest activity. The reaction was also affected greatly by organic solvents and their concentrations. It is found that protease in Newlase F does not hydrolyze amide bond under this condition (pH 7.0, r.t.).展开更多
The reactions of four different N-(O,O'-diisopropyl) phosphoamino acids (DIPP-aa), such as N-phosphoryl-L-α-alanine (DIPP- L-α-Ala), N-phosphoryl-D-α-alanine (DIPP-D-α-A1a), N-phosphoryl-β-alanine (DIPP...The reactions of four different N-(O,O'-diisopropyl) phosphoamino acids (DIPP-aa), such as N-phosphoryl-L-α-alanine (DIPP- L-α-Ala), N-phosphoryl-D-α-alanine (DIPP-D-α-A1a), N-phosphoryl-β-alanine (DIPP-β-A1a) and N-phosphoryl-γ-amino butyric acid (DIPP-γ-Aba), and four nucleosides, adenosine (A), guanosine (G), cytidine (C) and uridine (U), were studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and HPLC/ESI-MS. DIPP-L-α-A1a and DIPP-D-α-A1a produced the same phosphorylated nucleosides, dinucleotides and phosphoroligopeptide. However, DIPP-β-A1a and DIPP-γ-Aba gave no relevant products.展开更多
The positive and negative ESI-MS/MS spectra of N-ethoxy(phenyl) phosphoryl amino acids(EPP-AA) were investigated by electrospray ionization(ESI) ion trap mass spectrometry. The fragmentation pathways of [ M + N...The positive and negative ESI-MS/MS spectra of N-ethoxy(phenyl) phosphoryl amino acids(EPP-AA) were investigated by electrospray ionization(ESI) ion trap mass spectrometry. The fragmentation pathways of [ M + Na]^+ and [ M - H]^- ions are proposed and rationalized. The observation may have some potential applications in the interpretation of the MS/MS spectra of novel N-phosphoryl compounds. The complexity of MS/MS spectra of EPP-AA [ M + Na]^+ ions is decreased compared with that of N-dialkyloxyphosphoryl amino acid. Therefore, the new phosphonamidate method may be considered one of the superior methods that can be used in sequencing peptides and proteins extensively.展开更多
Hydrolysis procedure of N-diisopropyloxyphosphoryl phenylalanine (DIPP-Phe) has been studied by HPLCESI-MS. The hydrolysis products and intermediate were identified by HPLC-ESI-MS/MS. The results showed that (HO)(... Hydrolysis procedure of N-diisopropyloxyphosphoryl phenylalanine (DIPP-Phe) has been studied by HPLCESI-MS. The hydrolysis products and intermediate were identified by HPLC-ESI-MS/MS. The results showed that (HO)(i-PrO)P(O)Phe was intermediate in the hydrolysis process.……展开更多
The Atherton-Todd reaction has been extensively applied to the synthesis of phosphates and phosphoroami dates. [1] Zeng et al. [2] suggested that under Atheron-Todd reaction conditions, dialkyl phosphites are tran... The Atherton-Todd reaction has been extensively applied to the synthesis of phosphates and phosphoroami dates. [1] Zeng et al. [2] suggested that under Atheron-Todd reaction conditions, dialkyl phosphites are transformed into diakyl phosphorochloridates.……展开更多
The reaction of amino acids and phosphorus trichloride in THF was studied by 31P NMR tracing and ESI-MS/MS. A series of hydridophoranes and cyclic dipeptides were obtained. The reaction presented interesting diversity...The reaction of amino acids and phosphorus trichloride in THF was studied by 31P NMR tracing and ESI-MS/MS. A series of hydridophoranes and cyclic dipeptides were obtained. The reaction presented interesting diversity and the reaction mechanism was proposed. The mechanism suggests that phosphorus plays an important role in the synthesis of amino acid hydridophorane and cyclic dipeptides. The results also show that 31P NMR and ESI-MS/MS are useful tools for the investigation of reaction mechanism.展开更多
Daidzein (7,4'-dihydroxyisoflavone) was phosphorylated by a modified Atherton-Todd reaction. The structures of the five target product, were determined by X-ray, IR, NMR and ESI-MS. Electrospray ionization results ...Daidzein (7,4'-dihydroxyisoflavone) was phosphorylated by a modified Atherton-Todd reaction. The structures of the five target product, were determined by X-ray, IR, NMR and ESI-MS. Electrospray ionization results show that in the gas phase all the phosphorylated daidzein derivatives could form non-covalent complexes with the protein lysozyme, while non-covalent complexes were not detected in the mixed solution of daidzein with lysozyme. Relative affinity of every non-covalent complex was obtained according to its different decomposition orifice voltage.展开更多
The hydrolysis reactions of N-(O,O'diisopropyl)phosphoryl-L-α-alanine (DIPP-L-α-Ala), N-(O,O'diisopropyl)- phosphoryl-D-α-alanine (DIPP-D-α-Ala), N-(O,O'-diisopropyl)phosphoryl-β-alanine (DIPP-β-Al...The hydrolysis reactions of N-(O,O'diisopropyl)phosphoryl-L-α-alanine (DIPP-L-α-Ala), N-(O,O'diisopropyl)- phosphoryl-D-α-alanine (DIPP-D-α-Ala), N-(O,O'-diisopropyl)phosphoryl-β-alanine (DIPP-β-Ala) and N-(O,O'-diisopropyl)phosphoryl-γ-amino butyric acid (DIPP-γ-Aba), were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.展开更多
Electrospray ionization mass spectrometry (ESI-MS) is a powerful method for sequencing peptides. A novel fragmentation pattern with the loss of a neutral fragment of 45 Da was observed with the dipeptides, tripeptides...Electrospray ionization mass spectrometry (ESI-MS) is a powerful method for sequencing peptides. A novel fragmentation pattern with the loss of a neutral fragment of 45 Da was observed with the dipeptides, tripeptides, tetrapeptides and pentapeptides containing phenylalanine or histidine residues. A novel rearrangement reaction with the extrusion of a formamide piece was studied and the rearrangement mechanism was proposed and confirmed by deuterium labeling experiments with ESI-MSn and high-resolution mass spectrometry. These findings are poten-tially helpful in identifying the specific sequence pattern in the peptide sequencing.展开更多
Mass spectroscopic characteristics of phosphoryl amino acids were studied in detail by positive and negative electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). Be...Mass spectroscopic characteristics of phosphoryl amino acids were studied in detail by positive and negative electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). Be- sides N-diisopropyloxyphosphoryl amino acids (N-DIPP-AA), O-phospho- and O-diisopropyloxyphosphoryl amino acids (O-DIPP-AA) were studied and compared to N-DIPP-AA. The fragmentation pathways of [M+H]+, [M+Na]+ and [M-H]- ions of phosphoryl amino acids were summarized. In addition to several similar patterns, each of them showed its characteristic fragmention.展开更多
文摘A novel compound, diethyl puerarin-7-yl phosphate, was synthesized through a simplified Atheron-Todd reaction for the first time. The structure of this compound was elucidated by IR, ESI-MS and NMR. Two conformations of the compound were testified by 2D NMR (HSQC and HMBC) and dynamic NMR. Furthermore, we carried out the conformational analysis using chemical calculation by the Gaussian 03. Finally, we obtained two preferred conformations and energy values.
基金the National Natural Science Foundation of China (No. 29802006) the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE P.R.C. and Tsinghua University.
文摘The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.
基金supported by the National Natural Science Foundation of China (No. 20472076, 20572061, 20732004)Henan Academic Foundation of Science and Technology (No. 0512001400)
文摘5,7-Dimethoxy-2-phenylquinolin-4-yl phenyloxy (N-L-alanine ethyl ester) phosphoramidate (C28H29N2O7P, Mr = 536.17) has been synthesized by a facial phosphorylated reaction, and its structure was determined by IR, NMR, HR MS and X-ray single-crystal diffraction. The crystal belongs to triclinic, space group P1^-, with a = 11.375(2), b = 11.591(2), c = 11.638(2) A^°, α= 109.46(3), β= 104.58(3), γ= 100.48(3)°, V = 1339.6(5)A^°^3, Z = 2, Dc = 1.330 g/cm^3,μ = 0.152 mm^-1, F(000) = 564, the final R = 0.0654 and wR = 0.1546. In the crystal structure, the title compound is constructed by a centrosymmetric dimmer unit composed of a pair of π-π stacking diastereoisomers. The compound has a noteworthy feature in the framework, and such units are linked by two equal intermolecular P=O…H-N hydrogen bonds.
基金Supported by the National Natural Science Foundation of China(Nos20572058 and 20372041)Beijing Department of Education(NoXK100030514)
文摘Highly regioselective homocoupling of N,N-dialkylanilines can be achieved in water with cerium reagents, in which various N,N,N′,N′-tetraalkylbenzidines are obtained from N,N-dialkylanilines either by direct oxidation by cerium(Ⅳ)reagents or by cerium(Ⅲ) reagents in the presence of hydroperoxide.
基金The authors would like to thank the financial support of Beijing TH-UNIS-Insight Co.Ltd.and the National Natural Science Foundation of China (No.20132020) the Ministry of Science and Technology, the Chinese Ministry of Education and Tsinghua University.
文摘In this paper, we described an improved electrochemical method for synthesis of some 1-aryl-2-pyrrolidinecarbonitrile derivatives bearing an electron-withdrawing group (NO2). The electrochemical synthesis of titile compounds has been successfully performed in an undivided cell in reasonable yields.
文摘The crystal of the title compound, [Ni(C15HgBr2ClNO2)(C18H15P)(C10H7)](C18H15P), has been prepared and confirmed by X-ray diffraction. The crystal belongs to the triclinic system, space group PI with a = 9.991(3), b = 15.250(4), c = 18.542(5) A, α = 104.927(5), β = 104.009(6), γ = 94.422(6)°, V= 2619.2(11)A^3, Z = 2, Mr = 1140.91, Dc= 1.447 g/cm^3, F(000) = 1160 and μ(MoKα) = 2.053 mm^-1. The structure is refined to R = 0.0779 for 3773 observed reflections with I 〉 2σ(I) and wR = 0.1694 for 9026 unique reflections. The crystal (1-PPh3) is composed of neutral nickel(Ⅱ) complexes and co-crystallized PPh3 molecules. Intramolecular C-H...π interactions between C-H bond of the aldehyde group and phenyl ring of the coordinated PPh3 molecule in the nickel(Ⅱ) complex are observed, and intermolecular π-π interactions between neutral nickel(Ⅱ) complexes are also found in the crystal.
基金The authors thank the financial supports from the National Natural Science Foundation of China(No.20132020)the Ministry of Science and Technology,the Chinese Ministry of Education and Zhengzhou University.
文摘Different hydroxy substituted coumarins were successfully phosphorylated with diisopropylphophite (DIPPH) by the Atherton-Todd reaction in 76-89% yields. Moreover, the reaction activities of different hydroxys of the coumarins in the Atherton-Todd reaction were studied.
基金Supported by the National Natural Science Foundation of China(No.20572061).
文摘Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry(ESIMS) in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.
文摘Newlase F is a rude enzyme which contains triacylglycerol lipase and acid protease. Hydrolysis of dipeptide heptyl esters with Newlase F was studied in phosphate buffer-organic solvent by HPLC. When the Newlase F's level reached 5 mg/mL under mild condition (PH 7.0, 30 degreesC), the lipase had the highest activity. The reaction was also affected greatly by organic solvents and their concentrations. It is found that protease in Newlase F does not hydrolyze amide bond under this condition (pH 7.0, r.t.).
基金the National Natural Science Foundation of China(Nos.20572061,20672104)the Chinese Ministry of Education and Zhengzhou University for financial support.
文摘The reactions of four different N-(O,O'-diisopropyl) phosphoamino acids (DIPP-aa), such as N-phosphoryl-L-α-alanine (DIPP- L-α-Ala), N-phosphoryl-D-α-alanine (DIPP-D-α-A1a), N-phosphoryl-β-alanine (DIPP-β-A1a) and N-phosphoryl-γ-amino butyric acid (DIPP-γ-Aba), and four nucleosides, adenosine (A), guanosine (G), cytidine (C) and uridine (U), were studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and HPLC/ESI-MS. DIPP-L-α-A1a and DIPP-D-α-A1a produced the same phosphorylated nucleosides, dinucleotides and phosphoroligopeptide. However, DIPP-β-A1a and DIPP-γ-Aba gave no relevant products.
基金Supported by the Education Department of Henan Province(No. 200510459015).
文摘The positive and negative ESI-MS/MS spectra of N-ethoxy(phenyl) phosphoryl amino acids(EPP-AA) were investigated by electrospray ionization(ESI) ion trap mass spectrometry. The fragmentation pathways of [ M + Na]^+ and [ M - H]^- ions are proposed and rationalized. The observation may have some potential applications in the interpretation of the MS/MS spectra of novel N-phosphoryl compounds. The complexity of MS/MS spectra of EPP-AA [ M + Na]^+ ions is decreased compared with that of N-dialkyloxyphosphoryl amino acid. Therefore, the new phosphonamidate method may be considered one of the superior methods that can be used in sequencing peptides and proteins extensively.
文摘 Hydrolysis procedure of N-diisopropyloxyphosphoryl phenylalanine (DIPP-Phe) has been studied by HPLCESI-MS. The hydrolysis products and intermediate were identified by HPLC-ESI-MS/MS. The results showed that (HO)(i-PrO)P(O)Phe was intermediate in the hydrolysis process.……
文摘 The Atherton-Todd reaction has been extensively applied to the synthesis of phosphates and phosphoroami dates. [1] Zeng et al. [2] suggested that under Atheron-Todd reaction conditions, dialkyl phosphites are transformed into diakyl phosphorochloridates.……
基金Project supported by the National Natural Science Foundation of China (Nos. 20672104, 20732004)
文摘The reaction of amino acids and phosphorus trichloride in THF was studied by 31P NMR tracing and ESI-MS/MS. A series of hydridophoranes and cyclic dipeptides were obtained. The reaction presented interesting diversity and the reaction mechanism was proposed. The mechanism suggests that phosphorus plays an important role in the synthesis of amino acid hydridophorane and cyclic dipeptides. The results also show that 31P NMR and ESI-MS/MS are useful tools for the investigation of reaction mechanism.
基金Project supported by the National Natural Science Foundation of China (Nos. 20132020 and 20175026) and Henan Academic Foundation of Science and Technology.
文摘Daidzein (7,4'-dihydroxyisoflavone) was phosphorylated by a modified Atherton-Todd reaction. The structures of the five target product, were determined by X-ray, IR, NMR and ESI-MS. Electrospray ionization results show that in the gas phase all the phosphorylated daidzein derivatives could form non-covalent complexes with the protein lysozyme, while non-covalent complexes were not detected in the mixed solution of daidzein with lysozyme. Relative affinity of every non-covalent complex was obtained according to its different decomposition orifice voltage.
基金Project supported by the National Natural Science Foundation of China (Nos. 20572061, 20672104).
文摘The hydrolysis reactions of N-(O,O'diisopropyl)phosphoryl-L-α-alanine (DIPP-L-α-Ala), N-(O,O'diisopropyl)- phosphoryl-D-α-alanine (DIPP-D-α-Ala), N-(O,O'-diisopropyl)phosphoryl-β-alanine (DIPP-β-Ala) and N-(O,O'-diisopropyl)phosphoryl-γ-amino butyric acid (DIPP-γ-Aba), were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.
基金Project supported by the Chinese National Natural Science Foundation (No. 20175026) the Ministry of Science and Technology+1 种基金 the visiting scholar fund of the Chinese Education Ministry and Tsinghua University.
文摘Electrospray ionization mass spectrometry (ESI-MS) is a powerful method for sequencing peptides. A novel fragmentation pattern with the loss of a neutral fragment of 45 Da was observed with the dipeptides, tripeptides, tetrapeptides and pentapeptides containing phenylalanine or histidine residues. A novel rearrangement reaction with the extrusion of a formamide piece was studied and the rearrangement mechanism was proposed and confirmed by deuterium labeling experiments with ESI-MSn and high-resolution mass spectrometry. These findings are poten-tially helpful in identifying the specific sequence pattern in the peptide sequencing.
基金Project supported by the National Natural Science Foundation of China (No. 20175026).
文摘Mass spectroscopic characteristics of phosphoryl amino acids were studied in detail by positive and negative electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). Be- sides N-diisopropyloxyphosphoryl amino acids (N-DIPP-AA), O-phospho- and O-diisopropyloxyphosphoryl amino acids (O-DIPP-AA) were studied and compared to N-DIPP-AA. The fragmentation pathways of [M+H]+, [M+Na]+ and [M-H]- ions of phosphoryl amino acids were summarized. In addition to several similar patterns, each of them showed its characteristic fragmention.