The Incorporation of H3‐proline into the collagen of the periodontium of a rat

H3‐proline has been extensively used in the study of collagen metabolism of the periodontium. 1B order to determine what proportion of H3‐proline is actually incorporated into collagen, 24 hour incorporation of proline and its conversion to hydroxyproline was measured using microchemical techniques. The periodontal ligament of incisors, the gingivae, the palatal mucosa and the skin were collected and the specific activity of proline and hydroxyproline was determined. The results indicated that the specific activity of hydroxyproline was highest in the periodontal ligament, lower in gingivae and palatal mucosa, and lowest in skin. Most of the activity, however, was recovered in proline. The difference was mainly in the specific activity of the two amino acids. The proportion of radioactivity recovered in hydroxyproline varied from 13.9% in periodontal ligament, 8.3% in gingivae, to 6.6% in palatal mucosa. There appears to be a high rate of incorporation of H3‐proline into oral tissues, as previously reported. However, after 24 hours most of the H3‐proline is found in non‐collagenous proteins and not in collagen.