hypusine

Reference structure

ChEBI records hypusine as N6-[(2R)-4-amino-2-hydroxybutyl]-L-lysine, with formula C10H23N3O3 and CAS 34994-11-1. [ChEBI](https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI_21858)

1. Does the candidate structure match the side-chain attachment and both specified stereochemical configurations? definition
2. Which authoritative record or structural analysis supports the supplied identifier and stereochemical assignment? provenance

Context-specific identity

ChEBI distinguishes hypusine from hypusinate and from a hypusine residue; these relationships should be explicit when interpreting material records or molecular masses. [ChEBI](https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI_21858)

1. Does this record represent free hypusine, an ionic form or a covalently incorporated residue? boundary
2. Was the reported free analyte present before preparation or released from a peptide or protein? provenance

Deoxyhypusine hydroxylation

Deoxyhypusine hydroxylase catalyzes stereospecific hydroxylation of the deoxyhypusine residue in the eIF5A intermediate. This relationship does not establish that free hypusine is an equivalent enzyme substrate. [Assay of deoxyhypusine hydroxylase activity](https://pubmed.ncbi.nlm.nih.gov/21318876/)

1. Does the evidence distinguish hypusine-bearing material from deoxyhypusine-bearing material? measurement
2. Does a proposed enzyme experiment require a modified eIF5A substrate rather than the isolated amino acid? action

Localized residue evidence

The model requires a protein identity and localization evidence before attributing a hypusine measurement to a particular protein site.

1. Which organism, protein accession, isoform and residue-numbering convention identify the proposed host site? provenance
2. Is the assignment supported by a localized modified peptide or only by bulk hydrolysate measurement? measurement

Orthogonal identity evidence

The model records the evidence used to distinguish hypusine from lysine, deoxyhypusine, isomers and matrix interference rather than treating a nominal-mass match as conclusive.

1. Which retention, fragmentation, structural or stereochemical measurements support the assignment? measurement
2. Were authentic hypusine and relevant competing analytes tested under the same analytical conditions? provenance

Interpretable abundance

Free-pool concentration, total hypusine recovered after hydrolysis and protein-site occupancy are separate quantities requiring distinct preparation and normalization evidence.

1. What extraction, hydrolysis or derivatization steps were used, and how were recovery and analyte integrity checked? measurement
2. Does the reported value describe free concentration, total recovered amount or occupancy of a defined protein site? boundary

Hypusine-equivalent content

The model separates hypusine identity from counterions, water, residual solvents and impurities so that weighed mass can be interpreted correctly.

1. What salt stoichiometry, water content and assay basis determine the hypusine-equivalent content of this lot? measurement
2. Are lysine, deoxyhypusine and stereoisomer impurities controlled sufficiently for the intended assay? action

Supported use conditions

Solubility, stability, thermal properties and hazard classifications remain form- and condition-specific evidence requirements; missing values must remain unresolved.

1. Which measurements establish usable concentration and stability in the intended solvent, pH, temperature and storage interval? measurement
2. Which current safety documentation applies to this hypusine form and concentration, and what handling actions does it support? action

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of hypusine this model covers, and on what evidence? provenance

Identifiers and schemes

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these identifiers and schemes hold for the sense of hypusine this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of hypusine this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of hypusine this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of hypusine this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of hypusine this model covers, and on what evidence? provenance