Beta-carotene keeps enzymes active under heavy load

Enzymes are vital for metabolism and stimulate countless biological processes in humans, plants and industry. However, when submerged by an excess substrate, certain enzymes slow down – a phenomenon called inhibition of the substrate. This can lead to the effectiveness of drugs and industrial efficiency.

Researchers at the Munich Technical University (TUM) explored this mechanism and have found that beta-carotene can help counter it. The study is published in Nature communications.

Enzymes help wash our clothes, support digestion and increase bread. As a rule, the more they are given work, the more active they become. But around 20% of the known enzymes behave differently: when they are flooded with too many molecules at the same time, they slow down or even stop working entirely.

Until now, the inhibition of the substrate has not been well understood. Scientists think that he serves as a regulation mechanism within cells, but he can also turn against him.

“Laboratory experiences with certain drugs suggest that inhibition of the substrate can affect the functioning of drugs,” said Wilfried Schwab, professor of biotechnology of natural products in Tum. “When the drug concentrations are too high, the reaction can slow down.”

The same principle can affect efficiency in fields such as food production and industrial cleaning.

A plant enzyme for self -defense

Wilfried Schwab and his team have now demonstrated for the first time that the order in which molecules are linked to an enzyme can determine whether the inhibition of the substrate occurs. The team studied an enzyme of the tobacco plant which helps to convert phenols – accomplices to protective properties – in a form that can defend the plant against predators or pathogens.

The enzyme binds both to sugar molecules and phenols. The researchers observed that when sugar binds first, followed by phenol, the enzyme works normally. But when phenol is too often linked, the activity of the enzyme is inhibited. The more phenols present, the more this inhibitor sequence often occurs, which ends up blocking the defense response of the plant.

A competitive molecule facilitates the load

The team also made a second discovery: beta-carotene can mitigate this inhibition and restore enzymatic activity. It competes with phenols for the same liaison sites on the enzyme, preventing too many phenols from settling first and triggering the stop.

“This idea was based on previous results suggesting that beta-carotene can affect the inhibition of the substrate. However, we were surprised to see that beta-carotene could really reduce the inhibition of the substrate,” said Schwab.

But does that mean that beta-carotene can solve the problem at all levels?

“Beta-carotene is not a magic solution,” warns Schwab. “As with many systems, balance is essential for an appropriate enzymatic function. But our discovery opens up new directions for research – and can finally help improve processes through a wide range of applications.”