Human-specific evolutionary genetic loss of addition of a single oxygen atom from sialic acids increases hydrophobicity of cells and proteins.
Level 5 - mechanism / opinion, no new human data
Bench and in vitro molecular/cellular biophysical study without direct clinical or human in vivo data
PubMed 40198956 · doi:10.1016/j.carres.2025.109469
What was done
Researchers measured the biophysical effects of human-specific loss of CMP-N-acetylneuraminic acid hydroxylase (CMAH), which replaces N-glycolylneuraminic acid (Neu5Gc) with N-acetylneuraminic acid (Neu5Ac). They evaluated surface hydrophobicity using surface wetting contact angle measurements of Neu5Ac- and Neu5Gc-coated surfaces. They also used atomic force microscopy (AFM) with a hydrophobically modified probe to measure hydrophobic interaction frequencies on plasma sialoglycoproteins and engineered human lymphoma cells expressing differing ratios of Neu5Ac and Neu5Gc.
What was found
Surface wetting experiments demonstrated a 5 ± 2° difference in wetting angle between Ac- and Gc-coated surfaces. AFM studies showed that plasma sialoglycoproteins and engineered lymphoma cells expressing Neu5Ac exhibited a higher frequency of hydrophobic interactions with the probe compared to those expressing Neu5Gc (exact quantitative interaction values and frequencies were not reported in the abstract).
Why it matters
This provides a basic biophysical mechanism showing how the evolutionary loss of a single oxygen atom in sialic acid alters the surface hydrophobicity of human cells and proteins, potentially influencing molecular interactions and pathogen binding.
Limits
The study relies entirely on in vitro surface coatings, isolated plasma proteins, and an engineered human lymphoma cell line, without in vivo physiological validation. Exact sample sizes and quantitative AFM interaction metrics are omitted from the abstract.
Cited by
- supports Neu5Gc (N-glycolylneuraminic acid) and Neu5Ac (N-acetylneuraminic acid) differ in chemical structure by only a single oxygen atom.