Purification and some chemical properties of crystalline Euglena ferredoxin

Abstract A crystallization procedure for Euglena and Chlamydomonas ferredoxin is described. With minor modifications this method is applicable to all microalgae. The absorption spectrum of crystalline Euglena ferredoxin showed maxima at 276, 328, 422 and 465 nm, and a shoulder at approx. 285 nm. The ratios of absorbances at 328, 422 and 465 nm to that at 276 nm were very high, namely 0.87, 0.68, and 0.60, respectively. The molecular weight estimated from chemical and sedimentation analyses is 11 000 ± 1 000. The protein contained 2 g atoms of iron and acidlabile sulfide per mole. Euglena ferredoxin differed from higher plant ferredoxins in having more aspartic acid than glutamic acid. We failed to obtain ferredoxin from dark-grown cultures of Euglena.