Identification of Intermediates in the Biosynthesis of PR Toxin by Penicillium roqueforti

The sesquiterpenoid 7‐epi‐neopetasone was synthesized via the Wieland–Miescher ketone. The compound was identical to a previously tentatively identified headspace constituent of Penicillium roqueforti. Feeding experiments with ¹³C‐labeled mevalonolactone isotopomers demonstrated that oxidation at C12 and an isomerization of the C11?C12 to a C7?C11 double bond must occur independently and not via a C7‐C11‐C12 allyl radical in one step. Feeding with (11,12,13‐¹³C₃)‐7‐epi‐neopetasone resulted in labelling of the PR toxin, thus establishing this compound as a newly identified pathway intermediate.     

2‐Oxazoline Formation for Selective Chemical Labeling of 5‐Hydroxylysine

Hydroxylation of lysine, one of posttranslational modifications of proteins, generates 5‐hydroxylysine (Koh) and plays a crucial role in regulating protein functions in cellular activity. We have developed a chemical labeling method of Koh. The 1,2‐aminoalcohol moiety of Koh in synthetic peptide sequences was trapped by an alkyne‐containing benzimidate to form a 2‐oxazoline ring. An additional ammonia treatment process removed the undesirable amidine residue formed between benzimidate and lysine. During the ammonia treatment, the oxazoline residue formed at Koh mainly remained intact, and the ring opening to the amide form was observed for only part of oxazoline, indicating that the chemical labeling is amino acid selective. Azide‐substituted biotin or fluorescent dye was attached to the peptide through Huisgen cycloaddition at Koh and converted into an alkyne‐labeled oxazoline form. The Koh‐labeling assay could provide a platform to enhance proteomic research of lysine hydroxylation.     

Chronological protein synthesis in regenerating rat liver

Liver regeneration has been studied for decades; however, its regulation remains unclear. In this study, we report a dynamic tracing of protein synthesis in rat regenerating liver with a new proteomic technique, ³⁵S in vivo labeling analysis for dynamic proteomics (SiLAD). Conventional proteomic techniques typically measure protein alteration in accumulated amounts. The SiLAD technique specifically detects protein synthesis velocity instead of accumulated amounts of protein through ³⁵S pulse labeling of newly synthesized proteins, providing a direct way for analyzing protein synthesis variations. Consequently, protein synthesis within short as 30 min was visualized and protein regulations in the first 8 h of regenerating liver were dynamically traced. Further, the 3.5–5 h post partial hepatectomy (PHx) was shown to be an important regulatory turning point by acute regulation of many proteins in the initiation of liver regeneration.     

Protein Labelling with Versatile Phosphorescent Metal Complexes for Live Cell Luminescence Imaging

To take advantage of the luminescent properties of d⁶ transition metal complexes to label proteins, versatile bifunctional ligands were prepared. Ligands that contain a 1,2,3‐triazole heterocycle were synthesised using Cu^I catalysed azide–alkyne cycloaddition “click” chemistry and were used to form phosphorescent Ir^III and Ru^II complexes. Their emission properties were readily tuned, by changing either the metal ion or the co‐ligands. The complexes were tethered to the metalloprotein transferrin using several conjugation strategies. The Ir^III/Ru^II–protein conjugates could be visualised in cancer cells using live cell imaging for extended periods without significant photobleaching. These versatile phosphorescent protein‐labelling agents could be widely applied to other proteins and biomolecules and are useful alternatives to conventional organic fluorophores for several applications.     

三乙四胺钴配合物氧合结构和老化机理

以固相法合成的三乙四胺钴配合物为研究体系,采用正离子电喷雾串联质谱、紫外-可见吸收光谱、拉曼共振光谱和红外光谱等表征手段,研究了配合物与氧分子的相互作用过程及配合物在吸氧过程中的结构变化。结果表明,三乙四胺钴配合物的吸氧过程是一个动态的变化过程,氧合产物由双氧双桥联的氧合配合物CoⅢL-(O2)2-CoⅢL形式向双羟基桥联的老化配合物CoⅢL-(OH)2-CoⅢL形式转变;18O2同位素标记实验验证了Co-O-O-Co的存在。酸解实验说明OH桥联配合物的形成是造成可逆性差的根本原因。这些结果为探知多胺钴配合物的氧合结构和老化机理提供了新的研究方法和实验依据。     

两类图的(d,1)-全标号

主要讨论了W_n与C_m的笛卡尔积和均衡完全r-部图K_r(n)的(d,1)-全标号,并得出了(d,1)-全数λ_d~T(W_n□C_m)和λ_d~T(K_(r(n)))的确切值.     

A Whole Proteome Inventory of Background Photocrosslinker Binding

Affinity‐based protein profiling (AfBPP) is a widely applied method for the target identification of bioactive molecules. Probes containing photocrosslinkers, such as benzophenones, diazirines, and aryl azides, irreversibly link the molecule of interest to its target protein upon irradiation with UV light. Despite their prevalent application, little is known about photocrosslinker‐specific off‐targets, affecting the reliability of results. Herein, we investigated background protein labeling by gel‐free quantitative proteomics. Characteristic off‐targets were identified for each photoreactive group and compiled in a comprehensive inventory. In a proof‐of‐principle study, H8 , a protein kinase A inhibitor, was equipped with a diazirine moiety. Application of this photoprobe revealed, by alignment with the diazirine background, unprecedented insight into its in situ proteome targets. Taken together, our findings guide the identification of biologically relevant binders in photoprobe experiments.     

Synthesis of N,N‐Dialkylamino‐nor‐Dihydroxanthene‐Hemicyanine Fused Near‐Infrared Fluorophores and Their First Water‐Soluble and/or Bioconjugatable Analogues

The effective synthesis of extended conjugated N ,N ‐dialkylamino‐nor ‐dihydroxanthene‐based fluorophores is described from diversely functionalized salicylic aldehydes. The access to these original fluorescent derivatives proceeded in two steps through a one‐pot construction of the unusual nor ‐dihydroxanthene (nor ‐DHX) scaffold followed by a diversification step providing a wide variety of nor ‐DHX‐hemicyanine fused dyes emitting in the range of 730–790 nm. The versatility of our approach has enabled a further extension to the late‐stage introduction of negatively/positively charged polar groups onto their terminal nitrogen heterocyclic subunit, thereby giving access to the first water‐soluble and/or bioconjugatable members of this emerging class of NIR fluorophores. Our water‐solubilizing method is easily implementable, and the nor ‐DHX‐hemicyanine skeleton maintains satisfying fluorescence quantum yields (5–20 %) under physiological conditions. Finally, the bioconjugation ability of fluorescent derivatives bearing a free carboxylic acid was demonstrated through the covalent labeling of a model protein, namely, bovine serum albumin.     

糖胺聚糖的荧光标记及其与硫酸软骨素抗体的相互作用

以1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺和N-羟基琥珀酰亚胺为催化剂,将糖胺聚糖(肝素、硫酸乙酰肝素、硫酸软骨素A,B,C,D,E)中糖醛酸的羧基与氨基荧光素中氨基偶联,分别得到各荧光标记糖胺聚糖.将标记糖胺聚糖用点样仪点在硝酸纤维素包被玻璃芯片上,分别探讨其在硝酸纤维素薄膜上的保留率及其与硫酸软骨素抗体(克隆...     

Synthesis and application of isocyanates radiolabeled with carbon-11

Carbon-11 labeled isocyanates are efficiently prepared by dehydration of [(11) C]carbamate salts, which in turn are easily formed from cyclotron-produced [(11) C]CO(2) and amines in the presence of a CO(2) fixation agent. The [(11) C]isocyanates are useful radiosynthons for the synthesis of a variety of [carbonyl-(11) C]-labeled asymmetrical ureas and carbamate esters. The method is well suited to incorporate any isotope of carbon, and is especially useful for positron emission tomography (PET) radiotracers for in vivo imaging. This is demonstrated by using the method to make [carbonyl-(11) C]-6-hydroxy-[1,1'-biphenyl]-3-yl cyclohexylcarbamate which is a novel radiotracer for PET imaging of fatty acid amide hydrolase.