Chain scission of hyaluronan by peroxynitrite

Area of Science:

• Biochemistry
• Polymer Chemistry
• Free Radical Chemistry

Background:

• Peroxynitrite is a reactive nitrogen species implicated in oxidative damage.
• Hyaluronan is a crucial biopolymer in connective tissues.
• Understanding the interaction between peroxynitrite and hyaluronan is vital for elucidating biological damage mechanisms.

Purpose of the Study:

• To investigate the reaction mechanisms between peroxynitrite and hyaluronan.
• To quantify the yield of hydroxyl radicals generated during this reaction.
• To determine the contribution of different pathways to hyaluronan chain breakage.

Main Methods:

• Stopped-flow kinetics combined with gel permeation chromatography and multiangle laser light scattering.
• Analysis of hyaluronan chain break yields at varying peroxynitrite and hyaluronan concentrations.
• Quantification of free hydroxyl radical yield.

Main Results:

• Hydroxyl radicals escaping the peroxynitrite cage cause hyaluronan chain breaks, with a yield of 5+/-1%.
• Nitrite ions effectively scavenge hydroxyl radicals at high peroxynitrite concentrations.
• A bimolecular reaction between hyaluronan and ONOOH contributes an additional 3.5% chain breaks.

Conclusions:

• The primary mechanism of hyaluronan degradation by peroxynitrite involves hydroxyl radicals.
• Nitrite scavenging and direct polymer reaction with ONOOH are significant factors influencing chain break yields.
• The contribution of ONOOH isomerization to nitrate ions producing hydroxyl radicals is relatively low.