title: Isolation, purification and physicochemical characterization of water-soluble Bacillus thuringiensis melanin.
abstract: Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several technologies for the purification of water-insoluble dioxyphenylalanine (DOPA) melanins have been described, a source of water-soluble melanin is highly desirable. Here we describe an effective procedure for the isolation and purification of water-soluble melanin using the culture medium of Bacillus thuringiensis subsp. galleriae strain K1. Water-soluble melanin from this organism has an isoelectric point (pI=3.0-3.2) and was purified optimally by adsorbtion using the IA-1r resin and elution as a concentrated solution. The purified melanin obtained exhibited a similar infra-red absorbtion spectrum to synthetic melanin and contained quinolic and phenolic structures and an amino acid content of around 20% after acid hydrolysis. The molecular weight of the purified melanin determined by SDS-PAGE was 4 kDa and the electromagnetic spin resonance spectrum of the purified microbial melanin was a slightly asymmetric singlet without hyperfine structure with about 7 Gauss width of the line between points of the maximum incline and g=2.006. The concentration of paramagnetic centers in melanin is 0.21x10(18) spin/g. The results obtained provide a rapid, simple and inexpensive method for the large scale purification of water soluble melanin that may have widespread applications.
authors.affiliation: JSC, Institute of Biotechnology, 14.Gyurjian str. Yerevan, 375056, Armenia. armbiotech@netsys.am
authors.forename: Armen E
authors.initials: AE
authors.lastname: Aghajanyan
authors.forename: Artur A
authors.initials: AA
authors.lastname: Hambardzumyan
authors.forename: Anichka S
authors.initials: AS
authors.lastname: Hovsepyan
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Asaturian
authors.forename: Andranik A
authors.initials: AA
authors.lastname: Vardanyan
authors.forename: Ashot A
authors.initials: AA
authors.lastname: Saghiyan
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001413:Bacillus thuringiensis / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D007526:Isoelectric Point; D008543:Melanins / Q000737:chemistry* / Q000302:isolation & purification; D008970:Molecular Weight; D012995:Solubility; D014867:Water
chemical_list: D000596:Amino Acids; D008543:Melanins; D014867:Water