New Findings about the Inhibitory Action of Phenylcarbamates and Phenylthiocarbamates on Photosynthetic Apparatus

The inhibitory effect of alkyl-N-phenylcarbamates (alkyl = methyl-octyl) and alkyl-Nphenylthiocarbamates (alkyl = methyl-butyl) on the photosynthetic electron transport in spinach chloroplasts was studied. It was found that the site of action of the studied compounds is the intermediate D, i.e., the tyrosine radical located on site 161 in the D2 protein on the donor side of photosystem 2. The efficiency of the studied compounds was inversely proportional to the hydrophobicity of molecules, i.e., the effectiveness showed a decrease with increasing their hydrophobicity. It was found that alkyl-N-phenylcarbamates and alkyl-N-phenylthiocarbamates have the same site of action.