The lipocalin alpha(1)-microglobulin binds heme in different species.

摘要: Abstract The lipocalin α1-microglobulin (α1m), found in plasma and tissues of various vertebrates, is brown, forms complexes with other proteins has immunomodulatory effects vitro, but the physiological function not yet established. Human α1m was recently shown to bind heme and, after cleavage a C-terminal tetrapeptide, initiate degradation, thus suggesting heme-scavenger function. In this work heme-binding characterized using immobilized on agarose beads, spectrophotometry, electrophoresis. α1m, both purified form, displayed concentration-dependent binding heme–agarose. apparent dissociation-constant estimated be around 2 × 10−6 M for free IgA–α1m complex. Incubation resulted two different electrophoretic mobility. identified Western blotting, eluates from heme–agarose incubation human biological fluids as well sera non-human species, indicating evolutionary conservation property. Heme-binding could instrumental isolating new α1m-homologues.