Grossberg A L, Roholt O A, Pressman D
J Immunol. 1976 Jun;116(6):1596-600.
The phosphorylcholine binding mouse myeloma protein McPC 603 has been shown to have tyrosyl residues in its binding sites by the fact that iodination of the protein causes extensive loss of binding activity which can be substantially retained when the protein is iodinated with sites occupied by ligand. Paired label iodination of McPC 603 protein allowed identification of the tyrosine involved and showed the tyrosine to be in the heavy chain. Gel filtration of heavy chain peptides enabled the tyrosyl-containing peptide of interest to be identified as the N-terminal 33 residue peptide in which the only tyrosine is Tyr 33. Thus H chain Tyr 33 was shown to be a contact amino acid residue in the site of McPC 603 protein. These results provide chemical evidence confirming previously reported x-ray crystallographic identification of H chain Tyr 33 in the site of McPC 603 protein.
磷酸胆碱结合型小鼠骨髓瘤蛋白McPC 603已被证明在其结合位点含有酪氨酸残基，这是因为该蛋白碘化后结合活性大幅丧失，而当蛋白在配体占据位点进行碘化时，结合活性可基本保留。对McPC 603蛋白进行成对标记碘化可鉴定出相关酪氨酸，并表明该酪氨酸位于重链中。对重链肽进行凝胶过滤，使得含有所关注酪氨酸的肽段被鉴定为N端33个残基的肽段，其中唯一的酪氨酸是Tyr 33。因此，H链Tyr 33被证明是McPC 603蛋白位点中的一个接触氨基酸残基。这些结果提供了化学证据，证实了先前报道的通过X射线晶体学鉴定出的McPC 603蛋白位点中的H链Tyr 33。
