Biochemistry 4th Edition by Christopher Mathews,Kensal van Holde, Dean Appling, Spencer Anthony Cahill

Exercise 10

C. Servaites, in Plant Physiol. (1985) 78:839-843, observed that rubisco from tobacco leaves collected before dawn had a much lower specific activity than the enzyme collected at noon. This difference persisted despite extensive dialysis, gel filtration, or heat treatment. However, precipitation of the predawn enzyme by 50% (NH 4 ) 2 SO 4 restored the specific activity to the level of noon-collected enzyme. Suggest an explanation.