Relative Deficiency in Albumin Methionine Content is Associated With Decreased Antioxidant Capacity of Equine Plasma.

This research focuses on the role of methionine (MET) in the antioxidant capacity of plasma in horses and cows, finding that the low methionine content in equine albumin is correlated with reduced antioxidant capacity, increasing the susceptibility of horses to oxidative stress.

Objectives of the Research

• The main objective of this study was to analyze the redox status of equine plasma relative to bovine plasma, focusing on the role of methionine (MET) residues within albumin, a plasma protein.
• The research investigated whether equine albumin’s lack of MET residues resulted in a lower antioxidant capacity in equine plasma as compared to bovine plasma. This comparison would help discern if the unusual characteristic of equine albumin, having no methionine residues, would contribute to horses’ apparent higher susceptibility to oxidative stress.

Methodology

• Plasma samples were collected from healthy, nonpregnant Quarter Horse mares and adult, healthy, nonpregnant, dried Holstein cows.
• Multiple commercially available assays were used to assess measures of total antioxidant capacity and oxidative stress in these plasma samples. These assays included tests for total antioxidant capacity, thiol detection, thiobarbituric acid reactive substances (TBARS), and advanced oxidation protein products (AOPP).

Key Findings

• Significantly lower levels of thiol content and TBARS were found in horse plasma than in cow plasma, and higher levels of AOPP were detected.
• In spite of no observed difference in the total antioxidant capacity test, the study suggests a lower antioxidant capacity in equine plasma due to the absence of MET in equine albumin.

Implications of the Research

• This research strengthens the understanding of the importance of MET content within albumin for its antioxidant function. This has important implications for how horses could be treated or supplemented to better resist oxidative stress.
• It also highlights the complexity of the antioxidant defense system within the plasma, suggesting that there may be other factors that moderate or help to counteract oxidative stress.