N-α-acetyl-L-methionine | 94160-02-8

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 羧酸及其衍生物
• 英文名称: N-α-acetyl-L-methionine
• 英文别名: N-Ac-Met；AcMet；N-[(1S)-1-carboxy-3-methylsulfanylpropyl]ethanimidate
• CAS: 94160-02-8
• 化学式: C₇H₁₂NO₃S
• 分子量: 190.243
• InChiKey: XUYPXLNMDZIRQH-LURJTMIESA-M

计算性质

• 辛醇/水分配系数(LogP)：
  0.7
• 重原子数：
  12
• 可旋转键数：
  4
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.71
• 拓扑面积：
  94.5
• 氢给体数：
  1
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  N-α-acetyl-L-methionine 以 水 为溶剂， 生成
  参考文献：
  名称：

  ˙OH自由基诱导含蛋氨酸的肽脱羧。肽序列和净电荷的影响

  摘要：

  ˙OH自由基诱导的含蛋氨酸肽的氧化会导致蛋氨酸单元位置相对于末端功能（Met–Gly，Met–Glu，Met–Gly–Gly，Gly–Met -Gly，Gly-Met和Gly-Gly-Met），或具有位于蛋氨酸N-末端的相邻氨基酸（Ala-Met，β-Ala-Met，Val-Met，Leu-Met，Ser -Met，Thr-Met，His-Met，γ-Glu-Met，Pro-Met，Gly-Gly-Phe-Met和Tyr-Gly-Gly-Phe-Met）。γ-射线分解测得的CO 2产率从0％（Met–Gly，Met–Glu，Met–Gly–Gly，Gly–Met–Gly和Pro–Met）变化到约80％（γ–Glu–Met）可用的˙OH自由基。从机理上讲，脱羧被认为是通过分子内“外层”电子从甲硫氨酸羧酸盐官能团转移到氧化硫官能团S˙ +。γ-Glu-Met中存在一条额外的N末端脱羧途径，该途

  DOI：

  10.1039/p29910000353
• 作为产物：
  描述：

  N-[(1R)-1-carboxy-3-methylsulfanylpropyl]ethanimidate 生成 N-α-acetyl-L-methionine
  参考文献：
  名称：

  Structural Basis for Catalytic Racemization and Substrate Specificity of an N-Acylamino Acid Racemase Homologue from Deinococcus radiodurans

  摘要：

  N-acylamino acid racemase (NAAAR) catalyzes the racemization of N-acylamino acids and can be used in concert with an aminoacylase to produce enantiopure alpha-amino acids, a process that has potential industrial applications. Here we have cloned and characterized an NAAAR homologue from a radiation-resistant ancient bacterium, Deinococcus radiodurans. The expressed NAAAR racemized various substrates at an optimal temperature of 60 degrees C and had Km values of 24.8 mM and 12.3 mM for N-acetyl-D-methionine and N-acetyl-L-methionine, respectively. The crystal structure of NAAAR was solved to 1.3 A resolution using multiwavelength anomalous dispersion (MAD) methods. The structure consists of a homooctamer in which each subunit has an architecture characteristic of enolases with a capping domain and a (beta/alpha)7 beta barrel domain. The NAAAR.Mg2+ and NAAAR.N-acetyl-L-glutamine.Mg2+ structures were also determined, allowing us to define the Lys170-Asp195-Glu220-Asp245-Lys269 framework for catalyzing 1,1-proton exchange of N-acylamino acids. Four subsites enclosing the substrate are identified: catalytic site, metal-binding site, side-chain-binding region, and a flexible lid region. The high conservation of catalytic and metal-binding sites in different enolases reflects the essentiality of a common catalytic platform, allowing these enzymes to robustly abstract alpha-protons of various carboxylate substrates efficiently. The other subsites involved in substrate recognition are less conserved, suggesting that divergent evolution has led to functionally distinct enzymes.

  DOI：

  10.1016/j.jmb.2004.07.023

文献信息

• Nontargeted in vitro metabolomics for high-throughput identification of novel enzymes in Escherichia coli
  作者：Daniel C Sévin、Tobias Fuhrer、Nicola Zamboni、Uwe Sauer

  DOI：10.1038/nmeth.4103

  日期：2017.2

  A method to screen proteins for enzymatic activity by incubating purified or overexpressed proteins with a metabolite extract and measuring changes in metabolite abundance using mass spectrometry enables high-throughput characterization of functionally uncharacterized proteins in Escherichia coli. Our understanding of metabolism is limited by a lack of knowledge about the functions of many enzymes. Here, we develop a high-throughput mass spectrometry approach to comprehensively profile proteins for in vitro enzymatic activity. Overexpressed or purified proteins are incubated in a supplemented metabolome extract containing hundreds of biologically relevant candidate substrates, and accumulating and depleting metabolites are determined by nontargeted mass spectrometry. By combining chemometrics and database approaches, we established an automated pipeline for unbiased annotation of the functions of novel enzymes. In screening all 1,275 functionally uncharacterized Escherichia coli proteins, we discovered 241 potential novel enzymes, 12 of which we experimentally validated. Our high-throughput in vitro metabolomics method is generally applicable to any purified protein or crude cell lysate of its overexpression host and enables performing up to 1,200 nontargeted enzyme assays per working day.

  通过将纯化或过表达的蛋白质与代谢物提取物孵育，并使用质谱法测量代谢物丰度的变化，筛选蛋白质的酶活性，这种方法能够对大肠杆菌中功能未定的蛋白质进行高通量表征。我们对代谢的理解受到许多酶功能缺乏了解的限制。在这里，我们开发了一种高通量质谱法，用于全面分析蛋白质的体外酶活性。将过表达或纯化的蛋白质与含有数百种生物相关候选底物的补充代谢物提取物孵育，并通过非靶向质谱法确定累积和耗竭的代谢物。通过结合化学计量学和数据库方法，我们建立了一个自动化的管道，用于对新型酶的功能进行无偏注解。在筛选所有1275种功能未定的大肠杆菌蛋白质时，我们发现了241种潜在的新型酶，其中12种通过实验验证。我们的高通量体外代谢组学方法通常适用于任何纯化的蛋白质或过表达宿主的粗细胞裂解液，每个工作日最多可以进行1200次非靶向酶检测。
• Interactions of molybdocene dichloride with histidine- and methionine-containing peptides
  作者：Andrea Erxleben、Jessica Kottmann

  DOI：10.1016/j.ica.2005.05.019

  日期：2006.1

  The reaction behavior of the antitumor active metallocene dihalide Cp2MOCl2 (CP = eta(5)-cyclopentadienyl) towards AcHis, AcHis(1-Me), AcHis(3-Me), His-Gly, AcHis-Gly-His, AcMet, Gly-Met-Gly and cyclo-Met-Met has been studied in solution at 2.5 <= pD <= 7.4 by using H-1 NMR spectroscopy. The histidine-containing substrates were found to bind the Cp2Mo2+ unit through the terminal carboxylate group or through the NI nitrogen of the imidazole ring, depending on the pD value. At physiological pH, coordination takes place exclusively at the imidazole ring with the percentage Of Cp2Mo2+-His adducts in 1: 1 mixtures being about 70%. By contrast, the thioether group in the side chain of methionine has a very low affinity for the Cp2Mo2+ group. Monodentate S-coordination could not be detected. For AcMet, binding through the carboxylate group was observed as the only coordination mode, while in the case of Gly-Met-Gly Mo-S interaction occurs in combination with carboxylate coordination leading to a S,O-macrochelate in low yield. Coordination to metbionine peptides only takes place at pD <= 6, while at physiological pH interactions with the weak donor sites are not observed due to predominating dimerization Of [Cp2Mo(H2O)(OH)](+) to [(CpMo)-Mo-2(mu-OH)(2)MOCp2](2+). At c(Cl-) = 100 mM competitive Cl- coordination reduces the amount of carboxylate and S, O-coordination significantly, while imidazole coordination is not affected. (c) 2005 Elsevier B.V. All rights reserved.
• Structure–Stability–Activity Relationship in Covalently Cross-linked N-Carbamoyl d-Amino acid Amidohydrolase and N-Acylamino acid Racemase
  作者：Wei-Chun Chiu、Ji-Yu You、Jai-Shin Liu、Shih-Kuang Hsu、Wen-Hwei Hsu、Chien-Hua Shih、Jenn-Kang Hwang、Wen-Ching Wang

  DOI：10.1016/j.jmb.2006.03.063

  日期：2006.6

  N-Acylamino acid racemase (NAAAR) and N-carbamoyl-D-amino-acid amidohydrolase (D-NCAase) are important biocatalysts for producing enantiopure alpha-amino acids. NAAAR forms an octameric assembly and displays induced fit movements upon substrate binding, while D-NCAase is a tetramer that does not change conformation in the presence of a ligand. To investigate the effects of introducing potentially stabilizing S-S bridges in these different multimeric enzymes, cysteine residues predicted to form inter or intra-subunit disulfide bonds were introduced by site-directed mutagenesis. Inter-subunit S-S bonds were formed in two NAAAR variants (A68C-D72C and P60C-Y100C) and two d-NCAase variants (A302C and P295C-F304C). Intra-subunit S-S bonds were formed in two additional NAAAR variants (E149C-A182C and V265C). Crystal structures of NAAARs variants show limited deviations from the wild-type overall tertiary structure. An apo A68C-D72C subunit differs from the wild-type enzyme, in which it has an ordered lid loop, resembling ligand-bound NAAAR. The structures of A222C and A302C D-NCAases are nearly identical to the wild-type enzyme. All mutants with inter-subunit bridges had increases in thermostability. Compared with the wild-type enzyme, A68C-D72C NAAAR showed similar kcat/Km ratios, whereas mutant D-NCAases demonstrated increased kcat/Km ratios at high temperatures (A302C: 4.2-fold at 65 degrees C). Furthermore, molecular dynamic simulations reveal that A302C substantially sustains the fine-tuned catalytic site as temperature increases, achieving enhanced activity.
• Essential Roles of Zinc Ligation and Enzyme Dimerization for Catalysis in the Aminoacylase-1/M20 Family
  作者：Holger A. Lindner、Vladimir V. Lunin、Alain Alary、Regina Hecker、Miroslaw Cygler、Robert Ménard

  DOI：10.1074/jbc.m304233200

  日期：2003.11

  Members of the aminoacylase-1 (Acy1)/M20 family of aminoacylases and exopeptidases exist as either monomers or homodimers. They contain a zinc-binding domain and a second domain mediating dimerization in the latter case. The roles that both domains play in catalysis have been investigated for human Acy1 (hAcy1) by x-ray crystallography and by site-directed mutagenesis. Structure comparison of the dinuclear zinc center in a mutant of hAcy1 reported here with dizinc centers in related enzymes points to a difference in zinc ligation in the Acy1/M20 family. Mutational analysis supports catalytic roles of zinc ions, a vicinal glutamate, and a histidine from the dimerization domain. By complementing different active site mutants of hAcy1, we show that catalysis occurs at the dimer interface. Reinterpretation of the structure of a monomeric homolog, peptidase V, reveals that a domain insertion mimics dimerization. We conclude that monomeric and dimeric Acy1/M20 family members share a unique active site architecture involving both enzyme domains. The study may provide means to improve homologous carboxypeptidase G2 toward application in antibody-directed enzyme prodrug therapy.