# The Role of Ovalbumin in Manganese Homeostasis during Chick Embryogenesis: An EPR Spectroscopic Study

## TL;DR

This study explores how ovalbumin, a protein in chicken eggs, interacts with manganese to potentially protect embryos from toxicity.

## Contribution

The novel finding is that ovalbumin can bind manganese ions, possibly offering protection against manganese overload in chick embryos.

## Key findings

- Ovalbumin binds up to two Mn(II) ions, with one binding site showing slightly weaker affinity.
- Binding of Mn(II) does not alter ovalbumin's tertiary structure, as shown by fluorescence and UV/vis measurements.
- Bovine and human serum albumins bind Mn(II) more strongly than ovalbumin, likely due to differing physiological roles.

## Abstract

Ovalbumin (OVA), a protein vital for chick embryo nutrition, hydration, and antimicrobial protection, together with other egg-white proteins, migrates to the amniotic fluid and is orally absorbed by the embryo during embryogenesis. Recently, it has been shown that for optimal eggshell quality, the hen diet can be supplemented with manganese. Although essential for embryonic development, manganese in excess causes neurotoxicity. This study investigates whether OVA may be involved in the regulation of manganese levels. The binding of Mn(II) to OVA was investigated using electron paramagnetic resonance (EPR) spectroscopy. The results show that OVA binds a maximum of two Mn(II) ions, one with slightly weaker affinity, even in a 10-fold excess, suggesting it may have a protective role from Mn(II) overload. It seems that the binding of Mn(II), or the presence of excess Mn(II), does not affect OVA’s tertiary structure, as evidenced from fluorescence and UV/vis measurements. Comparative analysis with bovine and human serum albumins revealed that they exhibit higher affinities for Mn(II) than OVA, most likely due to their essentially different physiological roles. These findings suggest that OVA does not play a role in the transport and storage of manganese; however, it may be involved in embryo protection from manganese-induced toxicity.