KINGSTON, Ont. Surprising findings by Queens 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. Joness lab by undergraduate Biochemistry student Brendan OLeary, 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 teams findings are published on-line in the journal Proceedings of the National Academy of Sciences (PNAS). 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: Its remarkable. In biochemistry you rarely see that kind of predictive work from modeling mol
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Contact: Nancy Dorrance
nancy.dorrance@queensu.ca
613-533-2869
Queen's University
24-Jul-2007