Siv M. Tedro

Pseudomonas denitrificans cytochrome cc

Abstract The denitrifying bacterium, Pseudomonas denitrificans, yields a c-type cytochrome with many properties similar to those of hemoglobin and myoglobin. Presented is a detailed study of the chemical and physical properties of the Pseudomonas cytochrome including the amino acid sequence of the heme peptide. This cytochrome, initially isolated by Iwasaki and co-workers and termed “cryptocytochrome c,” can be classified as a cytochrome cc′, examples of which have been found previously only in the photosynthetic bacteria.

Amino acid sequence of high-redox-potential ferredoxin (HiPIP) isozymes from the extremely halophilic purple phototrophic bacterium, Ectothiorhodospira halophila.

The amino acid sequences of high-redox-potential ferredoxin (HiPIP) isozymes from Ectothiorhodospira halophila have been determined. These are: isozyme I, EPRAEDGHAHDYVNEAADPSHGRYQEGQLCENCAFWGEAVQDGWGRCTHPDFDEVLVKAEGWCSVYAPA S, and isozyme II, GLPDGVEDLPKAEDDHAHDYVNDAADTDHARFQEGQLCENCQFWVDYVNGWGYCQHPDFTDVLVRGEGW CSVYAPA. Isozyme II is the major form of HiPIP produced by the bacterium (65-80%) and is the most acidic of the known HiPIPs. The two isozymes are 72% identical to one another and require only a single residue deletion for alignment. Comparison of these HiPIPs with seven previously determined sequences revealed only 27% average identity. Both E. halophila HiPIP isozymes are likely to be functional since their sequences are equally distant from those of other species. The E. halophila HiPIP sequences show that H-bonding patterns recognized in Chromatium vinosum HiPIP are likely to be conserved and therefore cannot explain the unusually low redox potentials which have been reported.

Iron protein content of Thiocapsa pfennigii, a purple sulfur bacterium of atypical chlorophyll composition

Four out of five soluble electron transport iron proteins of Thiocapsa pfennigii plus the particulate cytochromes have been found to be analogous to those of Chromatium vinosum strain D. In addition to ferredoxin, high potential iron-sulfur protein. cytochrome c′, and cytochrome c-552(550), T. pfennigii contains a cytochrome c-552(545) not previously isolated from photosynthetic bacteria. It is concluded that T. pfennigii is more closely related to C. vinosum than to Rhodopseudomonas viridis, the only other known bacterial species having bacteriochlorophyll b.

The primary structure of chromatium high-potential iron-sulfur protein

The amino acid sequence of Chromatium high-potential iron-sulfur protein (“HiPISP”) is presented. This sequence is deduced from data obtained by enzymatic digestion of the denatured or chemically modified protein with trypsin, chymotrypsin, thermolysin, and carboxypeptidase A and by chemical degradation (Edman, BrCN) of modified and unmodified protein preparations.