reverse_translate

Convert a protein pool (or a protein sequence string) to a DNA pool by back-translating each amino acid to a codon. Two selection strategies are available: "first" always picks the most frequent codon (deterministic), while "random" samples from all synonymous codons (stochastic).

import poolparty as pp
pp.init()

Parameters

Parameter	Type	Default	Description
`pool`	`Pool \| str`	(required)	A `ProteinPool` or a protein sequence string (e.g. `"MKTL"`). DNA pools are not accepted.
`region`	`str \| list \| None`	`None`	Restrict translation to a named region or `[start, stop]` interval. `None` translates the entire sequence.
`codon_selection`	`str`	`"first"`	`"first"` uses the most frequent codon for each amino acid (deterministic). `"random"` samples uniformly from synonymous codons (stochastic — each draw may differ).
`num_states`	`int \| None`	`None`	Number of states. Only relevant with `codon_selection="random"`. `None` generates sequences on-the-fly.
`genetic_code`	`str \| dict`	`"standard"`	Genetic code to use. Pass a string identifier or a custom codon dictionary.
`iter_order`	`float \| None`	`None`	Enumeration order when combined with other pools.
`prefix`	`str \| None`	`None`	Prefix for the operation node name in the pool graph.

Note

The output sequence length is always 3 × the protein length (each amino acid maps to exactly one codon).

Note

Only the most commonly used parameters are shown above. For the full parameter list, see reverse_translate() in the API Reference.

Examples

Deterministic back-translation

codon_selection="first" (the default) always picks the same codon for each amino acid, producing a single fixed DNA sequence.

dna = pp.reverse_translate("MKTL")
dna.print_library()

dna: seq_length=12, num_states=1 ATGAAGACCCTG

Stochastic back-translation

codon_selection="random" samples from synonymous codons, so each draw may produce a different DNA sequence encoding the same protein.

dna = pp.reverse_translate("MKTL", codon_selection="random", num_states=4)
dna.print_library()

dna: seq_length=12, num_states=4 ATGAAAACGCTA
ATGAAAACGTTA
ATGAAAACGCTC
ATGAAGACGTTA

Chain: translate then reverse-translate

Round-trip a DNA sequence through protein and back — the resulting DNA may differ due to codon degeneracy, but the encoded protein is identical.

dna     = pp.from_seq("ATGAAACCCGGG")
protein = pp.translate(dna)
back    = pp.reverse_translate(protein, codon_selection="first")
back.print_library()

back: seq_length=12, num_states=1 ATGAAGCCCGGC

See reverse_translate().