The Effect of Hydroxymethanesulfonates on 14CO2 Photosynthesis by Algae
N. E. Tolbert 1 and J. L. Hess 1
From the
1 From the Department of Biochemistry, Michigan State University, East Lansing, Michigan 48823
Photosynthesis by the algae Chlamydomonas or Chlorella was altered in three major ways by treatment with 0.001 m 
-hydroxy-2-pyridinemethanesulfonate or hydroxymethanesulfonate. (a) At pH 7.6 or 8.3 these sulfonates restored the 14CO2-fixation rate to that which occurs normally at pH 6.5. This represented a 6- to 7-fold increase in rate at pH 8.3 over the rate in the nontreated algae. At pH 6.5 no stimulation of photosynthesis occurred. (b) In the presence of these sulfonates the algae accumulated much of the newly fixed 14C into sugar diphosphates, particularly ribulose diphosphate. During a 10- to 120-sec period at pH 8.3 about 18% of the total 14C fixed accumulated at a linear rate into ribulose diphosphate. At pH 6.5 the sulfonates also stimulated sugar diphosphate accumulation, but its conversion to 3-phosphoglycerate was more extensive. (c) At both pH 6.5 and 8.3 14C labeling of the amino acids was greatly inhibited by either sulfonate, and there was some increase in the percentage of 14C in pyruvate and -ketoglutarate. Although the reason for these changes in photosynthesis caused by the hydroxymethanesulfonates remains obscure, evidently the hydroxymethanesulfonates are not specific inhibitors of glycolate oxidase.
Treatment of the algae with the hydroxymethanesulfonates did not result in the accumulation of glycolate-14C as did occur in treated leaves of higher plants during 14CO2 photosynthesis. This result correlates with the absence of glycolate oxidase in algae. Thus, glycolate metabolism represents a major difference between algae and higher plants.
Submitted on May 31, 1966
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