Supramolecular assembly and acid resistance of Helicobacter pylori urease.
Level 5 - mechanism / opinion, no new human data
In vitro structural biology and biochemical assays (bench research).
PubMed 11373617 · doi:10.1038/88563
What was done
The authors resolved the crystal structure of Helicobacter pylori urease and performed enzymatic activity assays under various conditions to evaluate its stability and mechanism of acid resistance.
What was found
The crystal structure revealed a 1.1 MDa spherical supramolecular assembly of 12 catalytic units with an outer diameter of approximately 160 Å. Under physiologically relevant conditions, urease activity remained unaffected down to pH 3, with activity assays indicating that clustering of the 12 active sites on the supramolecular assembly is critical for enzyme survival at low pH.
Why it matters
This structural characterization explains how extracellular H. pylori urease can withstand gastric acid, resolving controversy regarding its stability and role in bacterial colonization of the gastric niche.
Limits
This is an in vitro laboratory study without in vivo animal or human data. Specific numerical kinetic rates, precise sample preparation sizes, and exact Km values are not reported in the abstract.
Cited by
- supports Helicobacter pylori utilizes the urease enzyme to neutralize stomach acid and create a microenvironment of neutral pH in the gastric mucosa.