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A new role for thioredoxin in assimilatory sulphate reduction
Author(s) -
Schwenn J.D.,
Schriek U.
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)81372-1
Subject(s) - thioredoxin , biochemistry , enzyme , spinach , thioredoxin reductase , chemistry , effector , biology
The activity of isolated APS‐kinase (EC 2.7.1.25) from the green alga Chlamydomonas reinhardii CW15 was stimulated by catalytic amounts of spinach thioredoxin f. The stimulation amounted to a factor of 3 in the presence of excess reducing thiols. A regulatory function of thioredoxin f was deduced from two observations: (a) the enzyme supported a low basal rate of PAPS formation in the absence of its effector, and (b) the saturation of the enzyme activity by thioredoxin f was sigmoidal. No evidence has been obtained of thioredoxin f serving as in the reduction of PAPS to sulphite in this alga. The slight increase in sulphite formation as observed with enriched spinach thioredoxin m is assumed to be due to a residual APS‐kinase contaminating the partially purified sulpho‐nucleotide unspecific sulphotransferase.