Overlooked Molecules in Metabolism

When muscles work intensively or brown adipose tissue produces heat in response to cold, metabolism shifts into high gear. Under these conditions, levels of so-called N-acetylated amino acids increase. These are chemically modified amino acids to which an acetyl group is attached. The functions of these molecules, however, remain largely unclear.

For a conceptual review paper, two researchers from Karlsruhe Institute of Technology (KIT) have now brought together findings from sports science, metabolism research, and cell biology and developed a new explanatory model. Their starting point was their own research: At KIT’s Institute of Sports and Sports Science (IfSS) at KIT, Professor Achim Bub and Dirk Weber had observed an increase in several N-acetylated amino acids during intense physical exercise. Similar findings have been reported for brown adipose tissue exposed to cold. Until now, these molecules have primarily been regarded as byproducts of protein degradation.

A Kind of Temporary Storage?

According to the authors, the studies reviewed suggest that this explanation may not be sufficient. Instead, N-acetylated amino acids could act as a kind of metabolic buffer by temporarily binding amino acids and acetyl groups and making them available again later. In this way, they could help maintain cellular energy and metabolic balance during periods of high metabolic activity.

“We propose a concept that adds a previously overlooked layer to metabolic regulation,” says Dirk Weber, doctoral researcher at the IfSS Exercise Physiology and Nutrition department. “Whether N-acetylated amino acids actually perform such a buffering function now needs to be investigated experimentally.” Future studies will therefore need to clarify how the “overlooked” molecules are formed, what role they play in different tissues, and whether they may also be relevant to metabolic diseases.

jha, August 18, 2026