Discussion 



Dr. Kauzmann: Among a few examples wherein denaturation is 

 accelerated by pressure is the denaturation of ovalbumin in urea at 

 0° C, which is accelerated by a factor of about 10 on applying 9000 

 psi (Simpson and Kauzmann, 1953). On the other hand, at 40° C 

 under the same conditions, there is no effect of pressure. One might 

 therefore expect that at still higher temperatures pressure would tend 

 to reverse or retard the denaturing effect of urea, in accordance with 

 the other examples of retardation of protein denaturation by pressure, 

 just discussed by Dr. Johnson. 



The work of Linderstr0m-Lang's group on the volume changes 

 which occur in the enzymatic hydrolysis of native beta lactoglobulin 

 also has some bearing on this point ( Linderstr0m-Lang, 1952); Lin- 

 derstr0m-Lang and Jacobsen (1941) ). These workers have found that 

 during the initial stages of degradation there is a volume decrease 

 amounting to several hundred cubic centimeters per mole. They have 

 ascribed this to a disruption of the native protein structure and have 

 given reasons for believing that this is akin to denaturation by agents 

 such as heat and urea. 



Dr. Mason: A good deal of evidence, especially with oxidative sys- 

 tems, has demonstrated that many enzymes tend to be aggregated, 

 possibly in a highly ordered way, upon intracellular particulates and 

 that their activities are dependent upon or modified by their order in 

 this aggregation. In considering the relationship between the response 

 of intact bioluminescent cells and extracts of those cells to changes 

 in environmental conditions such as pressure and temperature, is it 

 not possible that particulate suspensions and solutions of enzymes may 

 display qualitatively the same effects, yet be responding to the changes 

 in conditions by essentially different mechanisms? 



Dr. Johnson: That would seem possible, of course, but it would be a 

 more complicated interpretation of the results discussed. I do not 

 believe that the similarities of the pressure-temperature-inhibitor rela- 

 tionships of luminescence in the extracts to those in living cells are 

 merely coincidental, involving different mechanisms; in my opinion, 

 the evidence favors the view that they are fundamentally the same. 



297 



