Thiocalsin: a thioredoxin-linked, substrate-specific protease dependent on calcium.
1996; National Academy of Sciences; Volume: 93; Issue: 8 Linguagem: Inglês
10.1073/pnas.93.8.3169
ISSN1091-6490
AutoresIsabelle Besse, Joshua Wong, Kàroly Kobrehel, Bob B. Buchanan,
Tópico(s)Protein Hydrolysis and Bioactive Peptides
ResumoWe describe a protease, named "thiocalsin," that is activated by calcium but only after reductive activation by thioredoxin, a small protein with a redox-active disulfide group that functions widely in regulation. Thiocalsin appeared to be a 14-kDa serine protease that functions independently of calmodulin. The enzyme, purified from germinating wheat grain, specifically cleaved the major indigenous storage proteins, gliadins and glutenins, after they too had been reduced, preferentially by thioredoxin. The disulfide groups of the enzyme, as well as its protein substrates, were reduced by thioredoxin via NADPH and the associated enzyme, NADP-thioredoxin reductase. The results broaden the roles of thioredoxin and calcium and suggest a joint function in activating thiocalsin, thereby providing amino acids for germination and seedling development.
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