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Fmoc-N-Me-Glu(OtBu)-OH is a protected N-methyl-L-glutamic acid building block. The backbone nitrogen is methylated, the alpha nitrogen is protected as Fmoc, and the glutamate side-chain gamma-carboxyl group is protected as a tert-butyl ester.
Its purpose is to install a defined backbone N-methyl glutamate residue. That modification removes a backbone N-H donor and increases steric substitution at the amide nitrogen, which can change local conformation and peptide permeability.
Product Information
| Product Name | Fmoc-N-Me-Glu(OtBu)-OH |
| Catalog No. | AS2090 |
| CAS No. | 200616-40-6 |
| Molecular Formula | C25H29NO6 |
| Molecular Weight | 439.50 g/mol |
| Building Block Type | Fmoc-protected N-methyl-L-glutamic acid gamma-tert-butyl ester |
| Primary Applications | Backbone N-methylation; Fmoc-SPPS; conformational peptide design; macrocyclic and permeability-focused peptide SAR |
N-Methylation Changes the Peptide Backbone
N-methylation is not equivalent to modifying the glutamate side chain. It directly changes the amide nitrogen that becomes part of the peptide backbone. For comparison, Fmoc-Glu(OtBu)-OH produces ordinary L-Glu after deprotection and does not install backbone N-methylation.
Protecting-Group Logic
The gamma-carboxyl is protected as OtBu so that only the alpha-carboxyl participates in chain assembly. Fmoc is base-labile and OtBu is acid-labile, fitting conventional Fmoc/tBu orthogonality.
Coupling Can Be More Difficult
N-methyl amino acids are sterically more demanding than standard amino acids. Depending on the neighboring residue and sequence environment, double coupling, alternative activation or longer reaction times may be required. We prefer targeted optimization over applying stronger conditions indiscriminately.
Why Use N-Me-Glu in Peptide SAR
N-methyl residues are used to probe conformation, hydrogen-bonding networks, protease sensitivity and membrane permeability. These design principles are discussed further in Alan Scientific's noncanonical amino-acid overview.
Procurement and QC Considerations
Confirm CAS 200616-40-6, C25H29NO6, MW 439.50 g/mol, L configuration and N-methyl/OtBu protection. Supplier records also emphasize enantiomeric purity because LC-MS alone does not prove stereochemical identity.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.
Frequently Asked Questions
What does N-Me mean in this product?
It means the backbone amino nitrogen is methylated.
Which glutamate carboxyl is protected?
The side-chain gamma-carboxyl is protected as a tert-butyl ester.
Why can coupling be difficult?
The N-methyl substituent increases steric hindrance at the reacting amino-acid center.
Related Technical Resources
Review difficult coupling and side reactions
Discuss N-methyl peptide synthesis