Magnetic resonance imaging of tumor cells by targeting the amino acid transport system
摘要:
An early diagnosis of cancer is crucial in the battle against this disease and the in vivo visualization of tumors at cellular level is still the most challenging goal. In order to target tumor cells, we took into account their increased metabolism and amino acid nutrients or pseudo-nutrients, which are actively transported through the cell membrane, have been chosen as vectors for new MRI contrast agents. For this reason new gadolinium complexes conjugated to agmatine, arginine, and glutamine have been synthesized and studied. (c) 2006 Elsevier Ltd. All rights reserved.
A Lewis-acid-catalyzed method for the substrate-directed formation of peptide bonds has been developed, and this powerful approach is utilized for the new "remote" activation of carboxyl groups under solvent-free conditions. The presented method has the following advantages: 1) the high-yielding peptidesynthesis uses a tantalum catalyst for any amino acids; 2) the reaction proceeds without any racemization;
Tantalum-Catalyzed Amidation of Amino Acid Homologues
作者:Wataru Muramatsu、Hisashi Yamamoto
DOI:10.1021/jacs.9b08415
日期:2019.12.4
tantalum-catalyzed solvent-free approach for the construction of amide bonds with 1-(trimethylsilyl)imidazole is developed, and the mild reaction conditions are applicable to a wide variety of electrophilic aminoacid homologs. This approach delivers a new class of peptides in high yields without any epimerization.
Cyclic peptides containing a δ-sugar amino acid—synthesis and evaluation as artificial receptors
作者:Johan F. Billing、Ulf J. Nilsson
DOI:10.1016/j.tet.2004.11.024
日期:2005.1
An Fmoc-protected δ-sugar aminoacid, prepared by oxidation of a glucosamine derivative, was coupled to three different tripeptide tert-butyl esters (H-Tyr-Tyr-Tyr-OtBu, H-Tyr-Glu(OBzl)-Tyr-OtBu and H-Tyr-Arg(Mtr)-Tyr-OtBu) and the resulting sugar aminoacid/aminoacid hybrids were transformed into dimers that were subsequently cyclized to give three C2-symmetric macrocycles. The macrocycles were deprotected
通过氧化葡糖胺衍生物制备的Fmoc保护的δ糖氨基酸与三种不同的三肽叔丁酯(H-Tyr-Tyr-Tyr-O t Bu,H-Tyr-Glu(OBzl-的Tyr-O吨Bu和H-酪氨酸-精氨酸(MTR)-Tyr-O吨卜),将所得糖氨基酸/氨基酸杂交转化成随后被环化,得到3二聚体c ^ 2 -对称的大环化合物。将大环去保护,并检查它们对对硝基苯基糖苷,核苷酸和嘌呤的结合特性。在筛选的配体中,只有一些嘌呤显示出弱但显着的结合。
Peptide Bond Formation of Amino Acids by Transient Masking with Silylating Reagents
作者:Wataru Muramatsu、Hisashi Yamamoto
DOI:10.1021/jacs.1c02600
日期:2021.5.12
A one-pot peptide bond-forming reaction has been developed using unprotected amino acids and peptides. Two different silylating reagents, HSi[OCH(CF3)2]3 and MTBSTFA, are instrumental for the successful implementation of this approach, being used for the activation and transient masking of unprotected amino acids and peptides at C-termini and N-termini, respectively. Furthermore, CsF and imidazole
Biomimetic Peptide Catalytic Bond‐Forming Utilizing a Mild Brønsted Acid
作者:Erika Nakashima、Hisashi Yamamoto
DOI:10.1002/chem.202103989
日期:2022.6.21
flow synthesis at room temperature using organic solvents with boiling points below 100 °C. The method applies the tert-butoxycarbonyl amino methoxy group, forming the desired dipeptide without solvent at mild temperatures. Furthermore, the conversion of the carboxylic acid leaving the group to phenyl ester promotes peptide bond formation, and the reaction were applied to di, tri, and tetrapeptide bond