Ovalbumin is known to have six half-cystine residues with four thiol groups and one disulfide bond.Peptides containing the six half-cystine residues labelled with [2-14C]iodoacetic acid were isolated from pepsin digests of reduced and S-carboxyn1ethylated ovalbumin by gel filtration, paper ionophoresis and paper chromatography. These peptides were analysed for amino acids and sequenced by the dansyl-Edman procedure. Cysteic acid peptides, selectively recovered from enzyme digests of performic acid-oxidized ovalbumin, were used to confirm some sequences.The amino acid sequences around the two half-cystine residues involved in the disulfide bond were determined on cysteic acid peptides. These were derived from the disulfide-containing peptide of S-carboxymethylated ovalbumin after pepsin digestion and fractionation by gel filtration, ionophoresis at pH 1·8, performic acid oxidation and another ionophoresis by the diagonal technique.The disulfide-bond involves the sequences (A) -Asp-Lys-Leu-Pro-Gly-Phe-Gly-Asp-SerP-Ile-Glu-Ala-Gln-Cys-Gly-Thr-Ser-Val-Asxand (B) -Pro-Glu-Tyr-Leu-Gln-Cys-Val-Lys-Glu-. The thiol-containing sequences in ovalbumin are (C) -Tyr-Cys-Pro-Ile-Ala-Ile-Met-, (D) -Ala-Ala-Ser-Met-Glu-Phe-Cys-Phe-Asp-Val-Phe-Lys-, (E) -Phe-Gly-Arg-Cys-Val-Ser-Pro-, (F) -Phe-Cys-Ile-Lys-His-Ile-Ala-Thr-.

Myoglobin isolated from red muscle of the shark H. portusjacksoni was purified by ion-exchange chromatography on sulfopropyl-Sephadex and gel-filtration. Amino acid analysis and sequence determination showed 148 amino acid residues. The amino terminal residue is acetylated as shown by mass spectrographic analysis of N-terminal peptides. There is a deletion of four residues at the amino terminal end as well as one residue in the CD interhelical area relative to other myoglobins.The complete amino acid sequence has been determined following digestion with trypsin, chymotrypsin, pepsin and staphylococcal protease. Sequences of the purified peptides were determined by the dansyl-Edman procedure.The amino acid sequence showed approximately 85 differences from mammalian, monotreme and bird myoglobins. The date of divergence of the shark H. portusjacksoni from these other orders was estimated at 450 ± 16 million years, based on the number of amino acid differences between species and allowing for multiple mutations during .the evolutionary period. This estimate agrees well with similar estimates made using 0(-and fi-globin sequences, in contrast to widely differing estimates of dates of divergence for monotremes using the same three globin chains.Compared with myoglobins from species previously studied, there are many more differences in amino acid sequences, and in many positions residues are found that are more characteristic of 0(-and fi-globins, suggesting a conservation of residues over a long period of evolutionary time. There are fewer stabilizing hydrogen bonds and salt-linkages than in other myoglobins.

Myoglobin isolated from red muscle of the gummy shark M. antarcticus was purified by gel filtration and ion-exchange chromatography on carboxymethyl cellulose in 8 M urea-thiol buffer. Amino acid analysis and sequence determination showed 148 amino acid residues. The amino terminal residue is acetylated as shown by nuclear magnetic resonance and mass spectrographic analysis of an N-terminal peptide. There is a deletion of four residues at the amino terminal end as well as one residue in the CD interhelical area relative to other myoglobins. These overall differences were also found previously in myoglobin of Heterodontus portusjacksoni.The complete amino acid sequence has been determined following digestion with trypsin, chymotrypsin, thermolysin, staphylococcal protease and cyanogen bromide. Sequences of purified peptides were determined by the dansyl-Edman procedure. The amino acid sequence showed approximately 88 differences from mammalian, monotreme, bird and tuna myoglobins, slightly more than previously reported for H. portusjacksoni usually considered a more primitive animal. There were 24 residues common to both shark myoglobins that were different from those present in other myoglobins. The sequence has been compared to the myoglobin of yellowfin tuna and other myoglobins.

The tryptic peptides of the S-carboxymethylated globin chain ofa dimeric haemoglobin from A. trapezia were purified by high-performance liquid chromatography and their amino acid sequences determined by the dansyl-Edman method.The cyanogen bromide fragments were purified or digested with chymotrypsin to give overlap fragments which were sequenced by similar methods.In conjunction with some sequences of larger peptides derived by digestion with staphylococal protease, the complete sequence of 146 residues was deduced. The sequence has been compared with that previously determined for the 153 residue a-chain of the tetrameric haemoglobin from the same mollusc and shows 45% identity. In the E and F helical regions the homology is particularly noticeable with 75 and 100% identity respectively. The sequence of the dimeric haemoglobin chain of A. trazezia is very homologous (90% identity) to the published sequence of the similar haemoglobin from A. broughtonU. The homology when compared with other globin chains is much less, with approximately 20% identity in amino acid sequence.

The cyanogen bromide fragments of S-carboxymethylated fructose-bisphosphatase were purified. The amino acid sequences of the small fragments were determined by the dansyl-Edman method. The large fragments were subjected to proteolytic digestion to give smaller peptides more amenable for purification and sequencing by similar methods. Enzyme digests of the S-carboxymethylated enzyme gave overlap peptides containing the methionine residues.In conjunction with the amino acid sequence of the 60-residue N-terminal fragment previously determined on the S-peptide released by limited proteolysis with subtilisin the complete sequence of 336 residues was deduced. The sequence has been compared with the 335 residue sequence of pig kidney fructose-bisphosphatase and some areas of sequence for rabbit liver enzyme. The strong homology previously noted for the S-peptide sequences is maintained for the complete enzyme with only 34 changes in 336 residues when comparing the pig and sheep enzymes.