Amino Acid Sequence of the 'b5-like' Heme-Binding Domain from Chicken Sulfite Oxidase

Abstract

We present in this paper the sequence of the heme-binding domain of chicken sulfite oxidase, which can be obtained by chymotryptic digestion of the native enzyme. The results of an automatic degradation have been reported previously. In the present work peptides were obtained from the heme-binding domain by digestion with trypsin, chymotrypsin and Staphylococcus aureus V8 protease ; they were manually sequenced by the dansyl/Edman procedure. The evidence thus obtained is sufficient to completely establish the order of the 97 residues. In addition, two rounds of Edman degradation on sulfite oxidase itself allowed us to identify the same two residues, H-Ala-Pro, present at the N-terminus of the heme-binding domain; this result suggests that the latter constitutes the amino-terminal end of the sulfite oxidase peptide chain.The data presented here confirm the strong similarity between sulfite oxidase and microsomal cytochrome b5 already suggested by our first results. A sequence alignment is proposed for the two proteins. Inspection of the calf liver cytochrome b5 three-dimensional model together with the alignment suggests a similar overall structure for sulfite oxidase core with a limited number of backbone modifications. Our results point to a common evolutionary origin for sulfite oxidase core and microsomal cytochrome b5.

Refinement and structural analysis of bovine cytochrome b5 at 1.5 Å Resolution

“…In addition, there are several other b-type cytochrome fragments which show distinct sequence similarity to mammalian cytochrome bs, including rat outer membrane mitochondrial b5 (Lederer, Shrir, Guiard, Cortial & Ito, 1983) and the cytochrome domains from flavocytochrome b2 (Guiard, Groudinsky & Lederer, 1974), sulfite oxidase (Guiard & Lederer, 1979a) and assimilatory nitrite reductase (Le & Lederer, 1983). These sequences are approximately 30% identical to one another, indicating an evolutionary relationship between them and suggesting the occurrence of a comActa Crystallographica Section D ISSN 0907-4449 © 1996 mon structural motif, the 'cytochrome b5 fold' (Guiard & Lederer, 1979b).…”

Two Homologous Cytochromes b5 in a Single Cell

“…In the three-dimensional structure of the If one looks at the sequence of the other members of the family of bs-like cytochromes [34], one finds that the number of totally invariant residues has dropped from 15 to 13 with the substitutions found at position 15, which is discussed above, and a highly conservative one at position 79. Some of [44]; SO core = chicken sulfite oxidase heme-binding domain [12]. The sequences were aligned as in [34].…”

Study of a Zone Highly Sensitive to Proteases in Flavocytochrome b2 from Saccharomyces cerevisiae

“…Two-dimensional peptide separation on cellulose thinlayer plates was carried out according to Chen [I91 as described in [20]. Manual dansyl-Edman degradations, identification of dansyl amino acids and distinction between acids and amides were also carried out as described in [20].…”

“…Manual dansyl-Edman degradations, identification of dansyl amino acids and distinction between acids and amides were also carried out as described in [20]. Identification of protein N-terminal amino acids by dansylation in the presence of sodium dodecylsulfate was performed according to [21].…”