ACTIVATION OF ENZYMES DURING GERMINATION - TRYPSIN-LIKE ENZYME IN LETTUCE

In lettuce seeds trypsin-like enzyme activity develops during germination, and this process is inhibited by inhibitors of protein synthesis. The enzyme was purified more than 450 fold. It was shown that during germination in the presence of 35SO4, no radioactive sulphur was incorporated into the purified enzyme. Incorporation did take place into an acid phosphatase, which was also purified 110 fold. It is concluded that the trypsin-like enzyme does not arise by net protein synthesis. As the enzyme is formed an endogenous trypsin inhibitor disappears, due to enzymic destruction. It is suggested that the disappearance of the inhibitor controls the liberation of the trypsin-like enzyme from a precursor form. Possible mechanisms are discussed. The results are taken as further proof that during germination enzymes arise by liberation from inactive forms. © 1970.