Site-Directed Labeling of a Monoclonal Antibody: Targeting to a Disulfide Bond

Beverly Packard, Michael Edidin, Akira Komoriya

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We have designed and synthesized crabescein, the first member of a class of fluorescent labels that add across disulfide bonds. Crabescein is a fluorescein derivative that reports the rotational correlation time of the immunoglobulin G (IgG) segment to which it is covalently bound. Chemical analysis of the IgG labeled with crabescein indicates that the fluorophore is inserted into the third disulfide bond (cysteine-229 of mouse IgG2a) in the hinge region. The rotational correlation time of this labeled macromolecule was measured as a single exponential with a decay constant of 26.8 ns. This is in contrast to the double exponential with decay constants of 14.3 and 0.2 ns for the same IgG when labeled with fluorescein via a conventional labeling reagent in which the probe is bound to the macromolecule by one-point attachments. Thus, crabescein is the prototype of a class of fluorescent and phosphorescent probes that, by virtue of their two-point attachments to proteins, faithfully report on the dynamics of the segment of macromolecule to which they are covalently bound.

Original languageEnglish (US)
Pages (from-to)3548-3552
Number of pages5
Issue number12
StatePublished - Jun 1986

ASJC Scopus subject areas

  • Biochemistry


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