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Z-Arg(NO2)-OH is Nα-Cbz-Nω-nitro-L-arginine, a protected arginine derivative designed to keep both the α-amino group and the strongly basic guanidino functionality under control during peptide-bond formation. It belongs to a protection strategy that is more closely associated with protected-fragment and solution-phase chemistry than with routine Fmoc/Pbf SPPS.
For researchers reproducing established Z-based routes or building protected arginine-containing intermediates, the main practical issue is not simply whether arginine is protected. The exact protection map determines how the fragment can be activated, what other functional groups can be carried through the route, and how final deprotection must be scheduled.
Product Information
| Product Name | Z-Arg(NO2)-OH |
| Catalog No. | AS4088 |
| CAS No. | 2304-98-5 |
| Molecular Formula | C14H19N5O6 |
| Molecular Weight | 353.34 g/mol |
| Chemical Identity | Nα-Cbz-Nω-nitro-L-arginine |
| Building Block Type | Cbz-protected arginine derivative |
| Primary Applications | Protected arginine fragments, solution-phase peptide coupling, route reproduction and specialized peptide synthesis |
Why the Guanidino Group Is Nitro-Protected
Arginine is unusually challenging because its guanidino group remains strongly basic and can complicate activation, purification and protecting-group compatibility. Nω-nitro protection suppresses this functionality during synthesis. In our view, the important procurement check is the complete Nα-Cbz/Nω-nitro structure, not the abbreviated “Z-Arg” name alone.
Deprotection Must Be Planned as a Route
Cbz is normally removed reductively, and nitro-protected arginine chemistry also requires attention to reduction conditions. These operations should be evaluated together because a peptide or intermediate may contain alkenes, sulfur-containing groups or other reduction-sensitive functionality. Researchers comparing this chemistry with modern Fmoc workflows can use our practical guide to Fmoc solid-phase peptide synthesis as a protection-strategy reference point.
Coupling, Racemization and Fragment Quality
The α-carbon remains stereogenic, so prolonged activation and unnecessary base exposure should be avoided when epimerization is a concern. Protected amino-acid identity, coupling completion and stereochemical integrity are best considered together. Our discussion of racemization, deletion products and other peptide-synthesis side reactions provides additional context for why reaction monitoring matters even when a building block is already protected.
When This Building Block Is a Better Fit
Z-Arg(NO2)-OH is most useful when the synthetic route was intentionally designed around Cbz/nitro chemistry, when a protected arginine fragment is required, or when an established literature route is being reproduced. It should not be substituted one-for-one for Fmoc-Arg(Pbf)-OH without redesigning deprotection and protection compatibility. For sequences that require a custom route rather than a standard elongation cycle, Alan Scientific can evaluate the complete sequence through our custom peptide synthesis and protected-fragment service.
Procurement and QC Considerations
Confirm CAS 2304-98-5, formula C14H19N5O6, MW 353.34 g/mol and L-arginine stereochemistry on the lot-specific COA. The drawn structure should explicitly show Nα-Cbz and Nω-nitro protection. This is more informative than molecular mass alone when multiple protected arginine derivatives are handled in the same laboratory.
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
Is Z-Arg(NO2)-OH interchangeable with Fmoc-Arg(Pbf)-OH?
No. They use different temporary and side-chain protecting groups and therefore require different deprotection logic.
Why is the arginine side chain protected as a nitro derivative?
The nitro group suppresses guanidino reactivity during protected synthesis and fragment handling.
Is this mainly an SPPS building block?
It can be used in peptide chemistry, but it is particularly relevant to solution-phase, protected-fragment and legacy Z-based routes rather than standard repetitive Fmoc/Pbf SPPS.
Related Technical Resources
For other protection patterns, preassembled fragments and non-standard amino-acid reagents, browse our specialty peptide building block portfolio.