956 



CONCENTRATION FACTORS 



CITAP. 27 



in ordinary photosynthesis, hj^droxylamine also produces, albeit only 

 higher concentrations, two other inhibiting effects — on the reduction 

 of carbon dioxide by "hydrogen-adapted" algae (in which no oxygen is 

 liberated), and on the "de-adaptation" of such algae. Both effects could 

 be explained by the assumption that hydroxylamine has an affinity either 



800 



700 



600 



E 

 E 



N 



X 



500 



\- — • Scale of concentration 

 \ 10 times enlorged 



O 



o 



U- 



o 



Q. 



3 



400 



300 



200 



100 



U 01 2 3 0.4 0.5 6 



NH2OH • HCI CONCENTRATION 



Fig. 27.17. Influence of hydroxylamine chloride on carbon 

 dioxide reduction by Chromaiium (after Wassink, Katz and 

 Dorrestein 1942): 5% CCDo; 15% H.; pH 7.1G; 29° C; 

 strong light. NH^OH-HCl concentration in per cent. 



directly to the primary oxidation product Z (in photocomplex X- Chi -HZ), 

 or to an enzyme with which Z must react to prevent this primary product 

 from being lost by back reactions. 



New experiments of Wassink and co-workers (1942) showed that the 

 influence of hydroxylamine hydrochloride on the photoreduction of carbon 

 dioxide by purple bacteria {Chromatium) is somewhat stronger than the 

 above mentioned effect on the similar reaction in hydrogen-adapted 

 Scenedesmus. (The following figures show this relation: Normal photo- 

 synthesis of Scenedesmus, 50% inhibition at 5 X 10~^ mole/1.; photo- 



