Calcium-induced structural changes of cartilage proteoglycans studied by 1H NMR relaxometry and diffusion measurements

Research output: Contribution to journalResearch articleContributedpeer-review


  • Annett Werner - , Leipzig University (Author)
  • Wilfried Gründer - , Leipzig University (Author)


1H transverse nuclear magnetic relaxation times (T2) and self- diffusion coefficients (SDCs) of water were measured in isolated proteoglycan aggregates from pig articular cartilage. The influence of varying osmotic pressure, as well as of different calcium concentrations, on the samples was investigated. Due to a structural transition of the proteoglycans that results from changed electrostatic interactions at higher calcium concentrations, an additional fraction of water protons is observable. These protons are characterized by a very long T2 value and low, restricted diffusion. Additionally, electron microscopic elemental analyses and XFA investigations were performed to estimate the amount of calcium taken up by the proteoglycans. A model for the calcium-mediated structural transition of the cartilage proteoglycans is proposed that explains the experimental results. The investigations suggest the ability of proteoglycans to act as a calcium-concentrating agent and suggest their important role in the calcification process of articular cartilage.


Original languageEnglish
Pages (from-to)43-50
Number of pages8
Journal Magnetic resonance in medicine : an official journal of the International Society of Magnetic Resonance in Medicine
Issue number1
Publication statusPublished - 1999
Externally publishedYes

External IDs

PubMed 10025610
ORCID /0000-0001-8204-5699/work/154738454



  • H transverse relaxation, Calcium, Cartilage proteoglycans, PFG NMR, Structural transition