Four forms of bovine adrenodoxin with modified amino-termini obtained by direct expression of cDNAs in Escherichia coli are Ad(Met1), Ad(Met−1), Ad(Met−12), and Ad(Met6). The shoulder numbers represent this site of translation initiator Met at the amino-termini. The adrenodoxins, except for Ad(Met−1), were purified from the cell lysate and the ratios of A 414-to-A 276 of the purified proteins were over 0.92. NADPH-cytochrome c reductase activities of the three forms of adrenodoxin in the presence of adrenodoxin reductase were the same as that of purified bovine adrenocortical adrenodoxin. However, as cytochrome P-450SCC reduction catalyzed by Ad(Met0) was about 60% or that by Ad(Met1), the contribution of the amino-terminal region for the electron transfer or binding to cytochrome P-450SCC would need to be considered.
