---
title: "Get NucleotideMonomer by ID"
method: GET
path: "/api/v3/nucleotide-monomer/{nucleotide_monomer_id}"
tags: ["Nucleotide Monomer"]
---

# Get NucleotideMonomer by ID

`GET /api/v3/nucleotide-monomer/{nucleotide_monomer_id}`

## Request

- Base URL: `https://{tenant_name}.benchling.com`
- URL: `https://{tenant_name}.benchling.com/api/v3/nucleotide-monomer/{nucleotide_monomer_id}`
- Auth: HTTP bearer

Get a single NucleotideMonomer by ID.

## Path parameters

- `nucleotide_monomer_id` string, required

## Query parameters

- `returning` string[]
- `omit` string[]

## Headers

- `EARLY-ACCESS` string

## Response `200`

OK

- NucleotideMonomer: A building block component of modified oligonucleotides, representing a sugar, phosphate, or base subunit. Monomers are the chemical units that assemble to form nucleotides in therapeutic oligonucleotide design. Each monomer has a symbol identifier, chemical structure (SMILES), molecular weight, and attachment points defining where it bonds to other monomers. The naturalAnalog field links modified monomers to their natural counterparts (e.g., a 2'-O-methyl ribose analog links to natural ribose 'r'). Monomers are referenced in ModifiedNucleotide and CustomNotationAlias to specify the exact chemistry of modified sequences. Also known as building blocks in oligonucleotide synthesis contexts.
  - `__typename` string
  - `archiveReason` string, nullable
  - `archived` boolean
  - `attachmentPoints` string[]: A list of the capping group present at each location where the monomer can form a bond with other monomers.
  - `calculatedMolecularWeight` number, double, nullable: The molecular weight of the monomer as calculated by RDKit based on the monomer chemical structure.
  - `canonicalSmiles` string: The SMILES representation of the monomer chemical structure after being standardized.
  - `createdAt` string, datetime
  - `customMolecularWeight` number, double, nullable: Optional molecular weight value that the user can provide to override the calculated molecular weight.
  - `exactMolecularWeight` number, double: The exact molecular weight of the monomer as calculated by RDKit based on the monomer chemical structure.
  - `id` string
  - `modifiedAt` string, datetime
  - `monomerType` 'BACKBONE' | 'BRANCH': The part of the nucleotide structure that the monomer fits into, i.e. backbone or branch.
  - `name` string
  - `naturalAnalog` 'A' | 'C' | 'G' | 'T' | 'U' | 'N' | 'r' | 'd' | 'p' | 'R' | 'Y' | 'M' | 'K' | 'W' | 'S' | 'B' | 'D' | 'H' | 'V': Natural equivalent of the monomer. For example, a modified ribose would have `r` as the natural analog, which is the symbol for natural ribose.
  - `originalSmiles` string, nullable: The SMILES string that was originally provided upon creation of the monomer.
  - `polymerType` 'RNA': The polymer type of the monomer, per the HELM definition of polymer type. Because nucleotide monomers are only used in modified nucleotide sequences, the polymer type of a NucleotideMonomer is always `RNA`.
  - `symbol` string: User-defined identifier of the monomer, unique on the monomer type.
  - `visualColor` string, nullable: The color code of the monomer visual symbol.
  - `visualSymbol` 'DIAMOND_FILLED' | 'DIAMOND_HOLLOW' | 'DIAMOND_DASHED' | 'STAR_FILLED' | 'STAR_HOLLOW' | 'TRIANGLE_FILLED' | 'TRIANGLE_HOLLOW' | 'DYAD_FILLED' | 'DYAD_HOLLOW' | 'CLOVER_FILLED' | 'CLOVER_HOLLOW' | 'TRIAD_FILLED' | 'TRIAD_HOLLOW' | 'RECTANGLE_FILLED' | 'RECTANGLE_HOLLOW' | 'LETTERS_C' | 'LETTERS_CO' | 'LETTERS_M' | 'LETTERS_MP' | 'LETTERS_P' | 'LETTERS_PS' | 'LETTERS_R' | 'LETTERS_RS' | 'LETTERS_S' | 'LETTERS_SP': The shape of the monomer visual symbol.

## Other responses

- `400`: Bad Request
- `403`: Forbidden
- `404`: Not Found
- `429`: Too Many Requests
- `500`: Internal Server Error

---

[API](https://skmtc.dev/benchling/apis/benchling-api.md) - [All operations](https://skmtc.dev/benchling/apis/benchling-api/llms.txt) - [OpenAPI document](https://skmtc.dev/benchling/apis/benchling-api/revisions/c9f087b98b8b?raw)