A crosslinked cofactor in lysyl oxidase: redox function for amino acid side chains

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• Lysyl oxidase is crucial for collagen and elastin crosslinking in connective tissues.
• The active site of lysyl oxidase contains a redox cofactor essential for its catalytic activity.
• Previous research had not fully elucidated the precise structure of this cofactor.

Purpose of the Study:

• To identify and characterize the unknown redox cofactor in bovine aortic lysyl oxidase.
• To determine the structural basis and biogenesis of this novel cofactor.
• To expand the understanding of quinone cofactor diversity in biological systems.

Main Methods:

• Edman sequencing for protein N-terminal analysis.
• Mass spectrometry for precise mass determination and identification.
• Ultraviolet-visible (UV-Vis) spectroscopy for electronic structure analysis.
• Resonance Raman spectroscopy for vibrational mode analysis.

Main Results:

• A previously unidentified redox cofactor was discovered in bovine lysyl oxidase.
• Spectroscopic and sequencing data identified the cofactor as a quinone.
• The cofactor, designated lysine tyrosylquinone, is formed by crosslinking of a peptidyl lysine and a tyrosyl residue.
• This represents a unique example of a mammalian cofactor derived from two amino acid side chains.

Conclusions:

• The discovery of lysine tyrosylquinone expands the known repertoire of quinone cofactor structures.
• The unique biogenesis of this cofactor provides new insights into enzyme mechanism and evolution.
• Further studies are warranted to fully elucidate the implications for lysyl oxidase function and related biological processes.