# The role of the peptides in enzymes at the origin of live

## TL;DR

This paper investigates how peptide isomerization kinetics influence homochirality in biosystems, showing that water activity levels determine racemization or homochirality, which is crucial for understanding the origin of life and peptide aging.

## Contribution

The study combines thermodynamics and molecular dynamics simulations to reveal how water activity affects peptide racemization and homochirality, providing insights into the origin of life.

## Key findings

- High water activity promotes peptide racemization.
- Low water activity favors peptide homochirality.
- Hydrophobic cores in enzymes help maintain homochirality.

## Abstract

The peptides in biosystems are homochiral polymers of L-amino acids, but razemisate slowly by an active isomerization kinetics. The chemical reactions in biosystems are, however, reversible and what racemisates the peptides at the water activity in the biosystems can ensure homochirality at a smaller activity. Here we show by a thermodynamics analysis and by comprehensive Molecular Dynamics simulations of models of peptides, that the isomerization kinetics racemisates the peptides at a high water activity in agreement with experimental observations of aging of peptides , but enhances homochirality at a smaller water activity. The hydrophobic core of the peptide in an enzyme can ensure homochirality at a low water activity, and thus the establishment of homochirality at the origin of life and ageing of peptides and dead of biosystems might be strongly connected.