NN9535 Research

NN9535 is a synthetic analog of human GLP-1(7-37) that activates the GLP-1 receptor. Native GLP-1 is a substrate for dipeptidyl peptidase-4, which cuts it close to the N-terminus, and NN9535 was designed around that cleavage site. This article covers what laboratory research has measured, and in which system. Every finding below is labeled as a cell or in vitro assay, a named animal model, or a structural study.

What NN9535 is

NN9535 is a 31-residue peptide built on the human GLP-1(7-37) backbone, and its C-terminus is a free acid.

Sequence: H-Aib-E-G-T-F-T-S-D-V-S-S-Y-L-E-G-Q-A-A-K*-E-F-I-A-W-L-V-R-G-R-G-OH

Three features separate this chain from the native hormone.

• Aib, a non-coded residue, sits at position 2, which is position 8 in GLP-1 numbering.
• The lysine at position 20, marked K* above, carries a side chain of two AEEA units, then gamma-glutamic acid, then a C18 fatty diacid, octadecanedioic acid. Position 20 here is position 26 in GLP-1 numbering.
• Arginine at position 28, which is 34 in GLP-1 numbering, replaces the native lysine.

The CAS number is 910463-68-2, the UNII is 53AXN4NNHX, and the PubChem CID is 56843331. The molecular formula is C187H291N45O59 and the molecular weight is 4113.6 g/mol.

Research-grade material is characterized by its own analytical data, and the corresponding research-grade entry is Pure-SEM-1.

Why each modification is there

The discovery paper had two stated aims: higher albumin affinity, and full stability against metabolic degradation [1].

The Aib substitution guards the dipeptidyl peptidase-4 cleavage site. Its extra methyl group, on the alpha carbon, hinders the enzyme that cuts native GLP-1 after its second residue.

The arginine at GLP-1 position 34 leaves lysine 26 as the chain's only lysine, and the discovery paper reports derivatization at lysine 26 [1]. With one lysine left, an acylation reaction has one place to attach the side chain.

The acyl side chain is the feature intended to slow clearance, through reversible binding to albumin. The two AEEA units and the gamma-glutamic acid act as a spacer. The discovery paper names the fatty acid and the linking chemistry as the key features for albumin affinity, receptor potency and prolonged exposure [1].

Compared with an earlier acylated GLP-1 analog, the paper reports higher albumin affinity and three-fold lower receptor affinity [1].

What the GLP-1 receptor does when NN9535 binds

What follows is receptor-class background, not a finding about NN9535. The GLP-1 receptor is a class B1 G protein-coupled receptor, built to bind a peptide hormone. A large extracellular domain catches the C-terminal half of the peptide first, then the N-terminal residues insert into the transmembrane bundle. Activation of this receptor class couples it to Gs protein and raises intracellular cyclic AMP. The complexes resolved in the structural work below are receptor-Gs complexes [2].

The discovery paper measured binding to the GLP-1 receptor in vitro and reported an affinity of 0.38 nM [1]. That is an in vitro measurement, not an observation in a whole organism.

What the structural work shows

A cryo-electron microscopy study resolved the peptide bound to the GLP-1 receptor, captured in complex with Gs protein [2]. This is a structural study of a purified complex, so it measures no cellular response.

The structures showed peptide interactions similar to those of GLP-1 itself. The same study ran a cryo-EM variability analysis on the two agonist-bound complexes it resolved, and found different motions within the receptor and within the bound peptides [2]. Motions of that kind are inferred from density maps, so they describe the purified complexes only.

What animal studies report

Two of the three sources include work in named animal models, and both concern how long the peptide lasts and how it is cleared [1] [3]. In mini-pigs, the discovery paper measured a plasma half-life of 46.1 hours following intravenous administration [1]. That figure characterizes mini-pigs, because species differ in albumin and clearance.

How it is broken down and cleared in laboratory species

One study followed radiolabeled material through absorption, metabolism and excretion in humans, rats and monkeys [3]. Only the rat and monkey findings are described here.

In plasma, intact peptide was the main circulating component in both species [3]. Breakdown ran along two routes. Proteolysis cleaves the peptide backbone, and the fatty diacid side chain is shortened by sequential beta-oxidation, the standard catabolic route for fatty acids [3]. Metabolism was not confined to specific organs.

Labeled material was recovered in urine and feces, with urine the primary route [3]. Intact peptide accounted for less than 1% of the administered material in rat urine, and none was detected in monkey urine [3]. Clearance in those species therefore depended on breakdown rather than on excreting the molecule intact.

Human research

Human clinical studies of NN9535 have been published. This article does not summarize them. It covers what laboratory research has measured about the molecule itself: its structure, its receptor activity, and what cell, tissue and animal studies report.

Limits of the laboratory record

Two of the three cited papers came from the developer's own scientists [1] [3]. That is normal for a compound with this history, but it does mean limited independent replication. The structural work is the exception, from university laboratories [2].

A resolved structure directly observes the bound complex, but describes one state under one set of conditions. In vitro assays stop at receptor engagement, and animal findings belong to the species they were measured in.

Conclusion

NN9535 is unusually well described at the chemical level. Laboratory work explains why it binds albumin, why its N-terminus resists one specific enzyme, and how it engages its receptor. That record is strong on identity and mechanism, and silent on systems it never examined.

References

1. 1

   Lau J, Bloch P, Schäffer L, et al. J Med Chem. 2015;58(18):7370-80. PMID 26308095
2. 2

   Zhang X, Belousoff MJ, Liang YL, et al. Cell Rep. 2021;36(2):109374. PMID 34260945
3. 3

   Jensen L, Helleberg H, Roffel A, et al. Eur J Pharm Sci. 2017;104:31-41. PMID 28323117