136132-75-7

Upstream product

• 56-41-7 L-alanin 
• 28920-43-6 (fluorenylmethoxy)carbonyl chloride 
• 82911-69-1 N-(9H-fluoren-2-ylmethoxycarbonyloxy)succinimide 
• 102774-86-7 9-fluorenylmethyl N-succinimidyl carbonate 
• 88744-04-1 (9-fluorenyl)methyl pentafluorophenyl carbonate 
• 99503-04-5 Carbonic acid 3,5-dioxo-4-aza-tricyclo[5.2.1.0^2,6]dec-8-en-4-yl ester 9H-fluoren-9-ylmethyl ester 
• 146549-15-7 (2S)-N-<(fluoren-9-yl)methoxycarbonyl>alanine prop-2-enyl ester 
• 233281-32-8 N-(9-fluorenylmethyloxycarbonyl)alanine 3,4,5-tris(octadecyloxy)benzyl ester 
• 146346-88-5 methyl 2-(((9H-fluoren-9-yl)methoxy)carbonyl)aminopropanoate 
• 910126-27-1 Fmoc-Ala-MFE 
• 21715-90-2 N-hydroxy-5-norbornene-2,3-dicarboximide 
• 99502-89-3 Chlorameisensaeure-N-hydroxy-norborn-5-en-2,3-dicarboximidester 
• 68835-87-0 L-alanine dicyclohexylamine salt 
• 1227363-09-8 (AACAA)2 

Downstream Products

• 73724-40-0 (S)-2,5-dioxopyrrolidin-1-yl 2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)propanoate 
• 17195-26-5 Leu-Ala-Gly-Val 
• 141971-84-8 Ac-Tyr(t-Bu)-Gly-Gly-NH-Hex 

Relevant academic research and scientific papers

Reversible hydrogen transfer between cysteine thiyl radical and glycine and alanine in model peptides: Covalent H/D exchange, radical-radical reactions, and l - To D -Ala conversion

The reversible intramolecular hydrogen transfer reaction of peptide Cys thiyl radicals with Gly and Ala residues was studied in model peptides, where thiyl radicals were either generated through photochemical cleavage of disulfide bonds or through the rea

Heating and microwave assisted SPPS of C-terminal acid peptides on trityl resin: The truth behind the yield

Despite correct purity of crude peptides prepared on trityl resin by Fmoc/tBu microwave assisted solid phase peptide synthesis, surprisingly, lower yields than those expected were obtained while preparing C-terminal acid peptides. This could be explained

The first ratiometric fluorescent probes for aminopeptidase N cell imaging

In the current paper, three activity-based colorimetric and ratiometric fluorescent probes based on a naphthalimide fluorophore were well designed and synthesized, which can be recognized and hydrolyzed by aminopeptidase N (APN) at both the enzymatic and cellular level by following the fluorescent emission wavelength change from blue to green light. As a result, these molecules were successfully identified as the first ratiometric fluorescent probes for APN cell imaging.

Visible-light photoredox-catalyzed desulfurization of thiol- and disulfide-containing amino acids and small peptides

A scalable protocol for the desulfurization of cysteine by using visible light, the photocatalyst Ir(dF(CF3)ppy)2(dtb-bpy)PF6 and triethylphosphite under biphasic reaction conditions has been developed. The loading of the catalyst can be as low as 0.01?mol%, which can be efficiently removed during the workup (≤0.3?ppm), giving rise to the corresponding desulfurized product in high yields. This method has been applied also to cystine, penicillamine, and reduced and oxidized glutathione. The desulfurization has been found to be pH sensitive, with an optimal pH value of 6.5 and 7.0 for the cysteine derivatives and glutathione, respectively. In addition, during the desulfurization of a decapeptide containing cysteine and methionine, concurrent oxidation of the two sulfur-containing residues to disulfide and sulfoxide has been observed. Therefore, whereas the presented protocol allows a straightforward visible light-mediated desulfurization of simple thiols by using very low catalyst loading and a cost-effective trialkylphosphite as thiyl radical trapping agent, its application to complex substrates needs to be carefully validated. Copyright

Structure Revision of Similanamide to PF1171C by Total Synthesis

The total synthesis of the proposed structure of similanamide, a cyclic hexapeptide recently isolated from the marine sponge-associated fungus Aspergillus similanensis KUFA 0013, was achieved by solid-phase synthesis of a linear precursor and solution-phase macrolactamization. The NMR spectra of our synthetic final product were not identical to those of the isolated material and led us to conclude that similanamide is identical to PF1171C, a previously reported diastereomeric hexapeptide.

Solid phase synthesis without repetitive acidolysis. Preparation of leucyl-alanyl-glycyl-valine using 9-fluorenylmethyloxycarbonylamino acids.

The utility of repetitive nonhydrolytic base cleavage of alpha-amino protective groups in solid phase peptide synthesis is shown by a preparation of the model tetrapeptide leucyl-alanyl-glycyl-valine on a p-benzyloxybenzyl ester polystyrene--1% divinylbenzene resin support. Nalpha-9-Fluorenylmethyloxycarbonyl (Fmoc: Carpino & Han, 1970, 1972) amino acids were coupled by the symmetrical anhydride procedure, followed by Fmoc group cleavage using 50% piperidine in methylene chloride. Quantitative removal of the Fmoc-tetrapeptide from the solid support was effected by treatment with 55% trifluoroacetic acid in methylene chloride. Homogeneous free tetrapeptide was obtained in 87% overall yield. The procedure is proposed to offer advantages over present solid phase methods which use acidolysis for repetitive alpha-amino group deblocking.

COMPOUND FOR PREPARATION OF ANTIBODY-PAYLOAD CONJUGATE AND USE THEREOF

The present application relates to a novel linker for use in bioconjugation, comprising two or more electrophilic carbon atoms of a carbonyl group, and a click chemistry functional group and, more specifically, to a linker through which a compound, a peptide, and/or a protein can be directly and/or indirectly linked by a substitution reaction to a desired target molecule, that is, a target molecule.

Fungal Dioxygenase AsqJ Is Promiscuous and Bimodal: Substrate-Directed Formation of Quinolones versus Quinazolinones

Previous studies showed that the FeII/α-ketoglutarate dependent dioxygenase AsqJ induces a skeletal rearrangement in viridicatin biosynthesis in Aspergillus nidulans, generating a quinolone scaffold from benzo[1,4]diazepine-2,5-dione substrates. We report that AsqJ catalyzes an additional, entirely different reaction, simply by a change in substituent in the benzodiazepinedione substrate. This new mechanism is established by substrate screening, application of functional probes, and computational analysis. AsqJ excises H2CO from the heterocyclic ring structure of suitable benzo[1,4]diazepine-2,5-dione substrates to generate quinazolinones. This novel AsqJ catalysis pathway is governed by a single substituent within the complex substrate. This unique substrate-directed reactivity of AsqJ enables the targeted biocatalytic generation of either quinolones or quinazolinones, two alkaloid frameworks of exceptional biomedical relevance.

Mechanistic insight into metal ion-catalyzed transamination

Several classes of biological reactions that are mediated by an enzyme and a co-factor can occur, to a slower extent, not only without the enzyme but even without the co-factor, under catalysis by metal ions. This observation has led to the proposal that metabolic pathways progressively evolved from using inorganic catalysts to using organocatalysts of increasing complexity. Transamination, the biological process by which ammonia is transferred between amino acids and α-keto acids, has a mechanism that has been well studied under enzyme/co-factor catalysis and under co-factor catalysis, but the metal ion-catalyzed variant was generally studied mostly at high temperatures (70-100 °C), and the details of its mechanism remained unclear. Here, we investigate which metal ions catalyze transamination under conditions relevant to biology (pH 7, 20-50 °C) and study the mechanism in detail. Cu2+, Ni2+, Co2+, and V5+ were identified as the most active metal ions under these constraints. Kinetic, stereochemical, and computational studies illuminate the mechanism of the reaction. Cu2+ and Co2+ are found to predominantly speed up the reaction by stabilizing a key imine intermediate. V5+ is found to accelerate the reaction by increasing the acidity of the bound imine. Ni2+ is found to do both to a limited extent. These results show that direct metal ion-catalyzed amino group transfer is highly favored even in the absence of co-factors or protein catalysts under biologically compatible reaction conditions.

Novel chiral stationary phases based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin combining cinchona alkaloid moiety

Novel chiral selectors based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin connecting quinine (QN) or quinidine (QD) moiety were synthesized and immobilized on silica gel. Their chromatographic performances were investigated by comparing to the 3,5-dimethyl phenylcarbamoylated β-cyclodextrin (β-CD) chiral stationary phase (CSP) and 9-O-(tert-butylcarbamoyl)-QN-based CSP (QN-AX). Fmoc-protected amino acids, chiral drug cloprostenol (which has been successfully employed in veterinary medicine), and neutral chiral analytes were evaluated on CSPs, and the results showed that the novel CSPs characterized as both enantioseparation capabilities of CD-based CSP and QN/QD-based CSPs have broader application range than β-CD-based CSP or QN/QD-based CSPs. It was found that QN/QD moieties play a dominant role in the overall enantioseparation process of Fmoc-amino acids accompanied by the synergistic effect of β-CD moiety, which lead to the different enantioseparation of β-CD-QN-based CSP and β-CD-QD-based CSP. Furthermore, new CSPs retain extraordinary enantioseparation of cyclodextrin-based CSP for some neutral analytes on normal phase and even exhibit better enantioseparation than the corresponding β-CD-based CSP for certain samples.