[Modification of tryptophan residues in immunoglobulin M by 2-hydroxy-5-nitrobenzyl bromide].
The modification of tryptophan residues in monoclonal immunoglobulin M (IgM) by 2-hydroxy-5-nitrobenzyl bromide (RK) was studied at pH 2.0-2.85 and 7.0 and a RK to tryptophan molar ratio (K) from 1 to 40. At pH 2.85, the number of RK residues bound to IgM (N) in account to one HL-fragments does not exceed 10 (the HL-fragment of IgM contains 14 tryptophan residues); the plot of N vs K reaches a plateau at K greater than 20. When the pH is lowered to approximately 2, N rises to approximately 15, but the plateau is not reached. At pH 7.0, the modified IgM with N greater than 1 gives a sediment, while the product with N approximately equal to 1 remains in solution. Evidently, the latter contains the most accessible tryptophan residue (calculated per one HL-fragment). This residue was found to be one of the three residues localized in the C mu 2-domain and the adjoining N-terminal part. The possibility of multiple modification of tryptophan residues during the RK interaction with IgM in acid medium at high values of K is discussed.
D015077:2-Hydroxy-5-nitrobenzyl Bromide / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007075:Immunoglobulin M / Q000032:analysis*; D009596:Nitrophenols / Q000494:pharmacology*; D014364:Tryptophan / Q000032:analysis*; D008258:Waldenstrom Macroglobulinemia / Q000097:blood / Q000276:immunology
D000911:Antibodies, Monoclonal; D007075:Immunoglobulin M; D009596:Nitrophenols; D015077:2-Hydroxy-5-nitrobenzyl Bromide; D014364:Tryptophan
Modifikatsiia ostatkov triptofana v immunoglobuline M 2-oksi-5-nitrobenzilbromidom.