BREAKDOWN OF HEMOGLOBIN AND MYOHEMOGLOBIN 501 



Catalase prevents the formation of pentdyopent and it is therefore 

 doubtful whether the reaction can occur physiologically, except under 

 certain conditions which will be discussed in Chapter XI. 



It is also possible that pentdyopent is a product of secondary 

 oxidation of bilirubin or mesobilane, from which it is also formed by 

 hydrogen peroxide (373). In fact, it is not impossible that pentdyo- 

 pent may be an artifact, small amounts of it arising from the action 

 on bilirubin or mesobilane (but not on tetrahydromesobilane) of 

 hydrogen peroxide formed by autoxidation of dithionite, which is 

 used in the test. It has been found in some instances in urine which 

 did not contain bilirubin, but such urines may have contained 

 mesobilane. 



