[ tĕr′ĭ-dēn′ ]
Any of a group of organic compounds having two fused six-member rings each containing two nitrogen atoms and four carbon atoms. One of the rings is a pyrimidine, the other a pyrazine. Pteridines include folic acid and the pigments of butterfly wings.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.