PROPORTION OF INCORPORATION OF LEUCINE INTO ALBUMIN TO THAT INTO TOTAL PROTEIN IN RAT LIVER AND HEPATOMA MORRIS 5123 TC

Labelled serum protein appeared in the blood of normal and Morris hepatoma 5123 TC bearing rats 14 to 15 min after intracaval injection of radioactive leucine. Within this time albumin synthesis can be studied separately in vivo in liver and hepatomas. Tumor bearing rats were killed within 10 to 14 min after injection of [3H] or [14C]leucine. Postmitochondrial supernatants were prepared from 14C‐labelled liver and 3H‐labelled tumor, treated with sodium deoxycholate and combined. Albumin was purified from the mixture. The ratio [3H]protein to [14C]protein decreased during purification from 7 to 1.2, suggesting that the tumor synthesized less albumin compared to total protein than the liver. Radiochemically pure albumin was isolated from liver and tumor homogenates from rats killed within 12 to 14 min after injection of l‐[1‐14C]leucine. The specific radioactivity in albumin isolated from liver was 13 times higher than in that from tumor. The proportion of the incorporation of l‐[1‐14C]leucine into albumin to that into total protein was found to be 3.3% for liver and 0.8% for hepatoma homogenates. Copyright © 1969, Wiley Blackwell. All rights reserved