Thiol and disulphide contents of hen ovalbumin. C-terminal sequence and location of disulphide bond.
1. The thiol and disulphide contents of hen ovalbumin were investigated by p-chloromercuribenzoate titration, by determination of cysteic acid content after performic acid oxidation, by measurement of uptake of radioactive iodoacetic acid, and by assay of S-aminoethylcysteine after reaction with ethyleneimine. All results showed that ovalbumin had 6 half-cystine residues. Experiments with and without reducing agents demonstrated that there were 4 thiol groups and 1 disulphide bond. 2. A peptide containing equimolar amounts of S-carboxymethyl-cysteine, serine, valine and proline, but no lysine or arginine, was obtained by radioactive labelling of the cysteine residues with iodo[(14)C]acetic acid followed by electrophoretic and chromatographic separation of tryptic digests. It was concluded that the C-terminal sequence of ovalbumin is -Cys-Val-Ser-Pro. 3. The location of the disulphide bond was studied by using a double-labelling technique. It was shown that one end of the disulphide was located in this C-terminal peptide.
D000818:Animals; D002247:Carbon Isotopes; D002645:Chickens; D002729:Chloromercuribenzoates; D002845:Chromatography; D003545:Cysteine / Q000032:analysis; D004586:Electrophoresis; D005260:Female; D007097:Imines; D007461:Iodoacetates; D010047:Ovalbumin / Q000032:analysis*; D010455:Peptides / Q000032:analysis; D011392:Proline / Q000032:analysis; D012694:Serine / Q000032:analysis; D013440:Sulfides / Q000032:analysis*; D014357:Trypsin; D014633:Valine / Q000032:analysis
D002247:Carbon Isotopes; D002729:Chloromercuribenzoates; D007097:Imines; D007461:Iodoacetates; D010455:Peptides; D013440:Sulfides; D012694:Serine; D010047:Ovalbumin; D011392:Proline; D014357:Trypsin; D014633:Valine; D003545:Cysteine