FOOD CHEMISTRY
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2022
·
IF 9.231
Xue Xia,Yun Zhai,Heping Cui,Han Zhang,Khizar Hayat,Xiaoming Zhang,Chi-Tang Ho
The Amadori compound of glucose and l -alanyl- l -glutamine (Ala-Gln-ARP) was prepared and characterized by UPLC-MS/MS and NMR. There were no pyrazines produced by heated Ala-Gln-ARP alone due to the asynchronicity of regenerated l -alanyl- l -glutamine and α -dicarbonyl compounds. High temperature (130 °C) and long reaction time could facilitate the 2,5-dimethylpyrazine formation at a small concentration (33.4 ± 3.47 μg/L). The exogenous amino substrates would lower the formation temperature of pyrazines and make it to be generated effectively. Extra supplied l -alanyl- l -glutamine could generate 2,5-dimethylpyrazine at 110 °C, while higher temperature of 140 °C could strengthen the formation of 2,5-dimethylpyrazine (793 ± 119 μg/L) and stimulate the generation of other pyrazines, including methylpyrazine and 2,6-dimethylpyrazine. The exogenous alanine, glutamic acid, and glutamine was also beneficial to enhance the pyrazines formation, especially the glutamic acid. Furthermore, alkaline pH of thermal reaction made pyrazines increase significantly than in neutral medium and further enriched their species such as unsubstituted pyrazine and trimethylpyrazine.
研究领域:
食品化学
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有机化学
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分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Food Bioscience
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2024
·
IF 4.8
Jiaxuan Wang,Cuiping Pang,Zhonglin Tu,Jianghua Li,Guocheng Du,Guoqiang Zhang
L-Alanyl- l -Glutamine (Ala-Gln) is a kind of functional dipeptide , which is widely used in food and health care. Ala-Gln can be synthesized from l -glutamine and l -alanine methyl ester hydrochloride by α-Amino acid ester acyltransferase (AET). Still, the low catalytic efficiency and conversion rate of AET are key limiting factors in Ala-Gln production. In this study, the mutant library of AET were built based on structural model and semi-rational design. To facilitate the screening of AET mutants, the double enzymes coupled screening method was constructed and optimized. The amino acid residues I115, D203, F211, D300, A298, and R334 were selected as candidate mutation sites by alanine scanning and virtual saturation mutation and the catalytic activity of the optimal mutation A298C increased by 23.7%. Molecular dynamics simulation and molecular docking analysis suggested that the increased flexibility of the catalytic pocket in AET (A298C) and the formation of additional hydrogen bonds with substrate contributed to the improvement of enzyme activity .
研究领域:
生物化学
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酶工程
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食品科学
✓ 已验证
产品关联
DOI
高影响因子
Microbial Cell Factories
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2019
·Vol. 18
·期 1
·1-12
·
IF 4.402
Li Yi-Min,Gao Jiao-Qi,Pei Xu-Ze,Du Cong,Fan Chao,Yuan Wen-Jie,Bai Feng-Wu
Background l-Alanyl-l-glutamine (Ala-Gln) represents the great application potential in clinic due to the unique physicochemical properties. A new approach was developed to synthesize Ala-Gln by recombinant Escherichia coli OPA, which could overcome the disadvantages of traditional chemical synthesis. Although satisfactory results had been obtained with recombinant E. coli OPA, endotoxin and the use of multiple antibiotics along with toxic inducer brought the potential biosafety hazard for the clinical application of Ala-Gln.Results In this study, the safer host Pichia pastoris was applied as an alternative to E. coli. A recombinant P. pastoris (named GPA) with the original gene of α-amino acid ester acyltransferase (SsAet) from Sphingobacterium siyangensis SY1, was constructed to produce Ala-Gln. To improve the expression efficiency of SsAet in P. pastoris, codon optimization was conducted to obtain the strain GPAp. Here, we report that Ala-Gln production by GPAp was approximately 2.5-fold more than that of GPA. The optimal induction conditions (cultivated for 3 days at 26 °C with a daily 1.5% of methanol supplement), the optimum reaction conditions (28 °C and pH 8.5), and the suitable substrate conditions (AlaOMe/Gln = 1.5/1) were also achieved for GPAp. Although most of the metal ions had no effects, the catalytic activity of GPAp showed a slight decrease in the presence of Fe3+ and an obvious increase when cysteine or PMSF were added. Under the optimum conditions, the Ala-Gln generation by GPAp realized the maximum molar yield of 63.5% and the catalytic activity of GPAp by agar embedding maintained extremely stable after 10 cycles.Conclusion sCharacterized by economy, efficiency and practicability, production of Ala-Gln by recycling immobilized GPAp (whole-cell biocatalyst) is represents a green and promising way in industrial.
研究领域:
生物技术
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酶学
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药物化学
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合成生物学
✓ 已验证
DOI
PubMed
高影响因子
CRYSTENGCOMM
·
2024
·Vol. 26
·期 7
·943-950
·
IF 2.6
Jinqiu Fu,Mengyang Cai,Yuzhong Shi,Yihang Hou,Rongxi Guo,Chiyi Wang,Jingjing Zhao,Wei Zhuang,Hanjie Ying,Pengpeng Yang,Keke Zhang
L-Alanyl-L-glutamine (Ala–Gln) is a dipeptide which is widely used in medical and nutritional fields. Two new crystalline forms (form III and form IV) and a DMSO solvate form (SDMSO) of Ala–Gln were discovered in this study, which were distinguished from the known forms by Raman spectroscopy and powder X-ray diffraction (PXRD). Single crystal structures of the three new solid forms were obtained. Moreover, the crystal structure data of known forms: form II, dihydrate form (2H) and ethanol solvate form (SEtOH), which have not been reported to the best of our knowledge, were solved. The results showed that there were four kinds of molecular arrangements and frameworks in the Ala–Gln solid forms. The comparison of the molecular arrangements and cell parameters indicated that the forms III, 2H and SEtOH were isomorphic. The hydrogen bonding network of the DMSO solvate was different from those of forms II, III and IV. By comparing the bulk density, lattice energy and thermal analysis results of the three polymorphs of Ala–Gln, the order of bulk density and lattice energy was consistent with the decomposition enthalpy. Besides that, it was found that the crystal shape of the solvates can be retained after solvent removal.
研究领域:
药学
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晶体学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2023
·
IF 6.1
Xue Xia,Tong Zhou,Jingyang Yu,Heping Cui,Foxin Zhang,Khizar Hayat,Xiaoming Zhang,Chi-Tang Ho
The dynamic changes in fluorescence intensity of the Maillard reactions of l-alanyl-l-glutamine (Ala-Gln)/Diglycine (Gly-Gly)/glycyl-l-glutamine (Gly-Gln) and glucose were investigated. It was found that the fluorescence intensity would increase with the reaction time; however, it would decrease after longer heating at higher temperatures, which was accompanied by rapid browning. The strongest intensity occurred at 45, 35, and 35 min at 130 °C for Ala-Gln, Gly-Gly, and Gly-Gln systems, respectively. The simple model reactions of Ala-Gln/Gly-Gly and dicarbonyl compounds were selected to reveal the formation and mechanism of fluorescent Maillard compounds. It was confirmed that both GO and MGO could react with peptides to form fluorescent compounds, especially GO, and this reaction was sensitive to temperature. The mechanism was also verified in the complex Maillard reaction of pea protein enzymatic hydrolysates.
研究领域:
食品化学
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物理化学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOMATERIALS
·
2023
·
IF 14
Xinyue Ge,Hong Wen,Yang Fei,Rui Xue,Zhuo Cheng,Yanan Li,Kaiyong Cai,Liqi Li,Menghuan Li,Zhong Luo
Hydrogels are a class of biocompatible materials with versatile functions that have been increasing explored for the localized treatment of ulcerative colitis (UC), but various mechanical stimuli may cause premature hydrogel breakage and detachment, impeding their further clinical translation. Here we report a multifunctional mechanically-resilient self-healing hydrogel for effective UC treatment, which is synthesized through the host-guest interaction between dopamine/β-cyclodextrin-modified hyaluronic acid (HA-CD-DA) and amantadine-modified carboxymethyl chitosan (CMCS-AD). The excessive β-CD cavities allow the incorporation of dexamethasone (DEX), while the porous hydrogel network potentiates the encapsulation of basic fibroblast growth factor (bFGF) and L-alanyl- l -glutamine (ALG). DA moieties in HA components allow firm adhesion of the hydrogel to the ulcerative lesions after in-situ implantation, while the reversible host-guest interaction between CD and AD could enhance the persistence of hydrogel. The hydrogel demonstrated favorable biocompatibility and could continuously release DEX to induce M1-to-M2 repolarization of mucosal macrophages through inhibiting the toll-like receptor 4 (TLR4)-nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) axis. Furthermore, the co-delivered bFGF and ALG facilitates the regeneration of ulcerative mucosa and restore its barrier functions to ameliorate UC symptoms. The mechanically resilient hydrogel offers an integrative approach for UC therapy in the clinics.
研究领域:
药学
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生物医学工程
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材料科学
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炎症生物学
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胃肠病学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）