Enzyme discovery sheds light on vitamin D

Jul 24, 2007

Surprising findings by Queen’s University researchers have shed new light on how the “sunshine vitamin” D – increasingly used to treat and prevent cancer and other diseases – is broken down by our bodies.

“The effectiveness of vitamin D therapy is partly dependent on how quickly it will be broken down,” says Biochemistry Professor Glenville Jones, an expert in the field of vitamin D metabolism. “By studying the enzyme responsible for breaking down the vitamin, we hope to develop a way to prevent this from happening by blocking that response.”

First observed in Dr. Jones’s lab by undergraduate Biochemistry student Brendan O’Leary, the discovery reveals that changing a single amino acid in the hydroxylase enzyme will cause it to take a completely different pathway. Although scientists have known for 25 years that the enzyme is capable of taking two different pathways, until now they could not explain why this occurs.

The team’s findings are published on-line in the journal Proceedings of the National Academy of Sciences. Other members include: research associate David Prosser, PhD student Martin Kaufmann, and research technician Valarie Byford.

Earlier study of the enzyme had shown that its pathway pattern is species specific. Some species, including humans and rats, favour one pathway, while others – most notably the opossum – favour the other pathway.

Using a technique called liquid chromatography mass spectrometry, the researchers studied cells from animals in both categories. They changed the human enzyme in certain key places to see if this would affect its pathway pattern.

Surprisingly, they discovered that altering a single amino acid completely changes the enzyme from a human pattern to an opossum pattern. This change can be flicked back and forth “like a light switch,” says Dr. Jones, adding: “It’s remarkable. In biochemistry you rarely see that kind of predictive work from modeling molecules and enzymes.”

The Queen’s researchers believe the hydroxylase enzyme plays an important role in human cell functions. When vitamin D drugs are used in an attempt to arrest certain types of cancer, for example, the tumour responds by making more of this enzyme. “If we can block the tumour response, we should be able to successfully treat some tumours with vitamin D compounds,” says Dr. Jones, whose research is supported by the Canadian Institutes of Health Research.

Vitamin D deficiency has also been correlated with other diseases, including multiple sclerosis, muscle weakness, and bone-related disorders, he notes.

Source: Queen's University

Explore further: Inaccurate reporting jeopardizing clinical trials

Related Stories

'Map spam' puts Google in awkward place

6 hours ago

Google was re-evaluating its user-edited online map system Friday after the latest embarrassing incident—an image of an Android mascot urinating on an Apple logo.

Team develops faster, higher quality 3-D camera

6 hours ago

When Microsoft released the Kinect for Xbox in November 2010, it transformed the video game industry. The most inexpensive 3-D camera to date, the Kinect bypassed the need for joysticks and controllers by ...

Recommended for you

Inaccurate reporting jeopardizing clinical trials

11 hours ago

The team led by Dr Sheena Cruickshank of the Faculty of Life Sciences and Professor Andy Brass from the School of Computer Science analysed 58 papers on research into inflammatory bowel disease published between 2000 and ...

Fat signals control energy levels in the brain

Apr 23, 2015

An enzyme secreted by the body's fat tissue controls energy levels in the brain, according to new research at Washington University School of Medicine in St. Louis. The findings, in mice, underscore a role ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.