Three Americans won the Nobel prize for medicine yesterday for revealing the existence and nature of telomerase, an enzyme which helps prevent the fraying of chromosomes that underlies aging and cancer.

Australian-born Elizabeth Blackburn, British-born Jack Szostak and Carol Greider won the prize of 10 million Swedish crowns (€969,000), Sweden's Karolinska Institute said.

"The discoveries... have added a new dimension to our understanding of the cell, shed light on disease mechanisms, and stimulated the development of potential new therapies," it said.

The trio's work laid the foundation for studies that have linked telomerase and telomeres - the small caps on the end of chromosomes - to cancer and age-related conditions.

Work on the enzyme has become a hot area of drug research, particularly in cancer, as it is thought to play a key role in allowing tumour cells to reproduce out of control.

One example, a so-called therapeutic vaccine that targets telomerase, in trials since last year by drug and biotech firms Merck and Geron, could yield a treatment for patients with tumours including lung and prostate cancer.

The chief executive officer of Britain's Medical Research Council said the discovery of telomerase had spawned research of "huge importance" to the world of science and medicine.

"Their research on chromosomes helped lay the foundations of future work on cancer, stem cells and even human ageing, areas that continue to be of huge importance," Sir Leszek Borysiewicz said in a statement.

Dr Blackburn, a molecular biologist and biochemist known for her work on DNA and cell division, said she had not stayed waiting for a call from the Nobel Prize Committee, even though her name topped many Nobel prediction lists.