New York, Oct 11 (IANS): Researchers have identified an enzyme that has caused rifampicin -- a popular antibiotic used to treat bacteria that causes tuberculosis, leprosy, and Legionnaire's disease -- to become less effective and develop more resistance.

The actions of the enzyme Rifampicin monooxygenase -- a flavoenzyme which is a family of enzymes that catalyze chemical reactions essential for microbial survival -- have been found responsible for the antibiotic's resistance.

"Antibiotic resistance is one of the major problems in modern medicine," said Heba Adbelwahab, graduate student at Virginia Polytechnic Institute in the US.

Rifampicin, also known as Rifampin, has been used to treat bacterial infections for more than 40 years. It works by preventing the bacteria from making RNA, a step necessary for growth.

The findings represent the first detailed biochemical characterisation of a flavoenzyme involved in antibiotic resistance, the researchers said.

"Our studies have shown how this enzyme deactivates rifampicin. We now have a blueprint to inhibit this enzyme and prevent antibiotic resistance," Adbelwahab added.

Tuberculosis, leprosy, and Legionnaire's disease are infections caused by different species of bacteria. While treatable, the diseases pose a threat to children, the elderly, people in developing countries without access to adequate health care, and people with compromised immune systems.

For the study, the team used a special technique called X-ray crystallography to describe the structure of this enzyme.

They also reported the biochemical studies that allow them to determine the mechanisms by which the enzyme deactivates this important antibiotic.

The results were published in the Journal of Biological Chemistry and PLOS One.