Egg white proteins have many biological functions and substantial nutritional benefits when used as a food source; however, they also contain allergens such as ovalbumin, ovomucoid, and ovotransferrin. We prepared oligopeptides without allergens from hen egg whites via the use of several proteases, and assessed their effects on platelet aggregation and blood coagulation, known to both of which are known to be major risk factors in thrombogenesis. Egg white oligopeptides (EWOP) inhibited collagen-induced human platelet aggregation in a dose-dependent manner. Additionally, we attempted to determine whether cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), aggregation-inhibiting intracellular molecules, regulate EWOP-inhibited platelet aggregation. EWOP caused an increase in cAMP levels, but did not affect cGMP levels, which suggests that the anti-platelet activity of EWOP operates in a cAMP-dependent manner, rather than via a cGMP-dependent process, in collagen-induced platelet aggregation. In addition, EWOP induced a significantly prolonged prothrombin time (PT) as compared with the controls. These data show that EWOP inhibits the conversion of fibrinogen to fibrin in a plasmatic atmosphere on an extrinsic pathway. Accordingly, these findings suggest that EWOP may be an excellent candidate as a crucial inhibitor of platelet activation, and its anti-platelet effects appear to involve the inhibition of both platelet aggregation and blood coagulation within the cardiovascular system.

When cyanobacterium cells are grown under extremely low CO(2) concentration, the number of carboxysomes, structures containing ribulose-bisphosphate carboxylase (Rubisco; EC 4.1.1.39), is known to increase. This suggests that Rubisco helps to regulate photosynthesis in cyanobacteria. However, no studies have been done on the changes of Rubisco content and activity in response to the extracellular CO(2) concentration, and no information is available on its effect on photosynthesis. To elucidate the relationship between the expression responses of Rubisco and extracellular CO(2), wild-type cells (Synechococcus PCC7942) and carboxysome-lacking cells were grown under various CO(2) concentrations, and Rubisco activity was determined. In both strains, Rubisco activity increased when the cells were grown under a CO(2) concentration around, or less than, K (1/2)(CO(2)) of photosynthesis. In carboxysome-lacking cells, Rubisco activity increased five to six times at most, and a simultaneous increase in the rate of photosynthesis was observed. These results suggest that stimulation of expression of Rubisco occurs to compensate for the decrease in the rate of photosynthesis under CO(2)-limited conditions.