Separation of the tryptic peptides and cyanogen bromide fragments of the human embryonic zeta chains of hemoglobin in Portland I and II by reverse phase high performance liquid chromatography.
Anahtar kelimeler
Öz
The amino acid compositions of tryptic peptides and cyanogen bromide fragments of the purified zeta chain of Hb Portland I (zeta 2 gamma 2) and Hb Portland II (zeta 2 beta 2) have been determined. The hemoglobins were obtained from blood from neonates with hydrops fetalis due to homozygous alpha-thalassemia. The globin chains, tryptic peptides and cyanogen bromide fragments were all separated by reverse phase high performance liquid chromatography (HPLC). Several different types of C-18 columns were used with two different developer systems. The tryptic peptides of aminoethylated zeta chain were separated using an ammonium acetate-acetonitrile gradient. An aqueous trifuoroacetic acid-1-propanol developer gradient was used for the separation of cyanogen bromide fragments. Of the seventeen tryptic peptides obtained, two (zeta T10a and zeta T10b) resulted from the unusual cleavage of a Tyr-Ile peptide bond. This was observed even when using TPCK treated trypsin. From this study and results of others, it can be deduced that trypsin will hydrolyze the Tyr-X bond provided either Ala or Ile is bonded to the N-terminal side of Tyr and Ile, Leu, or Gly is bonded to the C-terminal side of the Tyr residue.