Study finds hormone for growth has enzyme role

Researchers at University College Galway have discovered an unexpected role played by a hormone which controls bovine growth. The work opens up a new avenue of study of human illnesses related to growth hormones, such as dwarfism, giantism and thyroid deficiencies.

The research was carried out at UCG's Department of Biochemistry under Dr John Donlon, who discovered that a bovine hormone can also take on the functions of an enzyme.

"Growth hormone may be doing things that we hadn't anticipated, and these might be very important," he said.

Hormones are among the most powerful biochemicals and control functions throughout the body. They act like free-moving switches circulating in the bloodstream and then connecting themselves to tissues, affecting the way they perform.

Growth hormones regulate the way something develops, switching on or turning off its internal chemistry to suit appropriate growth. Growth-related defects occur when this highly-complex process does not take place correctly.

Enzymes are very different biochemicals but are equally vital for the normal functioning of an organism. They act as catalysts, controlling the rate of a biological reaction without being used up in the reaction. Their power lies in changing one biochemical substance into another, helping the many reactions which surround all biological functions.

Dr Donlon's work suggests that hormones may be working at a completely different level, starting as hormones and ending up doing the work of enzymes.

He was looking at a bovine enzyme, attempting to trace it back to its chemical origins. "In the course of studies of a particular enzyme we found its original activity was associated with growth hormone. It opens up interesting possibilities that growth hormone has a dual function as a hormone and as an enzyme," Dr Donlon said.

This work related to bovine hormone so the next step would be to establish whether this "dual functionality" also occurred in human growth hormone. "I have a gut feeling that the same is likely to pertain in humans."