Synthesis of Nitrate Reductase in Chlorella: I. EVIDENCE FOR AN INACTIVE PROTEIN PRECURSOR 1

AUTOR(ES)

Funkhouser, Edward A.

RESUMO

Synthesis of nitrate reductase (EC 1.6.6.1) in Chlorella vulgaris was studied under inducing conditions, i.e. with cells grown on ammonia and then transferred to nitrate medium. Cycloheximide (but not chloramphenicol) completely inhibited synthesis of the enzyme, but only if it was added at the start (i.e. at the time of nitrate addition) of the induction period. Cycloheximide inhibition became less effective as induction by nitrate proceeded. Enzyme from small quantities of culture (1 to 3 milliliters of packed cells) was purified to homogeneity with the aid of blue dextran-Sepharose chromatography. Incorporation of radioactivity from labeled arginine into nitrate reductase was measured in the presence and absence of cycloheximide. Conditions were found under which the inhibitor completely blocked the incorporation of labeled amino acid, but only slightly decreased the increase in nitrate reductase activity. The results indicate that synthesis of nitrate reductase from amino acids proceeds by way of a protein precursor which is inactive enzymically.

Documentos Relacionados

• Synthesis of Nitrate Reductase in Chlorella: II. EVIDENCE FOR SYNTHESIS IN AMMONIA-GROWN CELLS 1
• The Nitrate Reductase of Chlorella: Species or Strain Differences
• Evidence for an Inactivating System of Nitrate Reductase in Hordeum vulgare L. during Darkness That Requires Protein Synthesis 1
• Effects of Cation Levels of the Nutrient Medium on the Biochemistry of Chlorella: I. Concentration Series 1
• Regulation of Nitrate Reductase in Chlorella vulgaris1