Histone 5 stains metachromatically with Coomassie Blue R-250, a property shared only with collagens and procollagens, histones 1 and 2B, and possibly certain proline-rich salivary gland proteins. 2. Coomassie Blue-stained goose and chicken H5 induce the same degree of metachromasia, which is intermediate between that induced by H1 and H2b. 3. The absorption spectra of all Coomassie Blue-stained gel bands consist of a primary maximum at 555 nm, but the absorption spectra of H5 gel bands also include a prominent shoulder in the vicinity of 525 nm, a region in which H1 gel bands display a secondary maximum. 4. The possible role of proline-rich sequences in the induction of metachromasia is discussed.
