Assay of Pteridines with Crithidia fasciculata*
Aided by grants from the Rockefeller Foundation, the American Cancer Society, the U. S. Public Health Service, and the Loomis Institute.
Abstract
SYNOPSIS. Detailed directions are given for the preparation of a simplified assay medium and of natural materials for assay of pteridines with Crithidia fasciculata. Unconjugated pteridines in natural materials which also contain conjugated pteridines (folic and folinic acids) can be assayed by destroying the conjugated pteridines with acid hydrolysis, which does not appreciably alter Crithidia-active unconjugated pteridines. The widespread occurrence of unconjugated pteridines and their significance in such processes as photoreception are discussed.