Changes in some enzyme activities and DNA content in frozen stored and freeze-dried bovine thymus

The effect of the preservation method and storage time of bovine thymus on the activity of adenosine deaminase (ADA) and purine nucleoside phosphoryla se (PNP), as well as on the quantity changes of desoxyribonucleic acid (DNA ), was studied in this work. Fresh bovine thymus was divided into 3 groups. The first one was frozen and stored at -12 degrees C, the second at -30 de grees C: and the third was freeze-dried. The last was placed in air-tight c ontainers and stored at 4 degrees C. Every 2 months during 20 months of sto rage, the activity of ADA and PNP by the Kalckar method and DNA content by the diphenylamine method were determined. Lowest activities of ADA and PNP were in freeze-dried samples while the highest were found for the frozen sa mples stored at -12 degrees C. DNA content was at nearly the same level thr oughout the storage time. If fresh thymus is not available for the producti on of drugs containing the analysed enzymes and DNA, it is sufficient to fr eeze it. In this state the gland remains stable for nearly 2 years. (C) 199 9 Elsevier Science Ltd. All rights reserved.