The presence of heat-labile factors interfering with binding analysis of fibrinogen with ferritin in horse plasma.
BACKGROUND
Horse fibrinogen has been identified as a plasma specific ferritin-binding protein. There are two ways in the binding of ferritin-binding protein with ferritin: one is direct binding and the other is indirect binding which is heme-mediated. The aim of this study was to analyze the binding between horse fibrinogen and ferritin.


RESULTS
Although fibrinogen in horse plasma did not show the binding to ferritin coated on the plate wells, after following heat-treatment (60°C, 30 min) of horse plasma, plasma fibrinogen as well as purified horse fibrinogen bound to plates coated with horse spleen ferritin, but not with its apoferritin which lost heme as well as iron after the treatment of reducing reagent. Binding of purified or plasma fibrinogen to ferritin was inhibited by hemin and Sn-protoporphyrin IX (Sn-PPIX), but not by PPIX or Zn-PPIX.


CONCLUSIONS
Heat-treatment of horse plasma enabled plasma fibrinogen to bind to plate well coated with holo-ferritin. From the binding analysis of fibrinogen and ferritin, it is suggested that horse fibrinogen recognized iron or tin in complexed with the heme- or the hemin-ring, and also suggest that some fibrinogens circulate in the form of a complex with ferritin and/or heat-labile factors which inhibit the binding of fibrinogen with ferritin.
Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Aomori 034-8628, Japan. orino@vmas.kitasato-u.ac.jp.
Kazuma
K
Takahashi
Takashi
T
Kondo
Yasunaga
Y
Yoshikawa
Kiyotaka
K
Watanabe
Koichi
K
Orino
D000818:Animals; D005293:Ferritins / Q000737:chemistry / Q000378:metabolism*; D005340:Fibrinogen / Q000737:chemistry / Q000378:metabolism*; D006427:Hemin; D006736:Horses / Q000097:blood*; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008665:Metalloporphyrins; D011485:Protein Binding; D011524:Protoporphyrins; D014001:Tin / Q000737:chemistry / Q000378:metabolism
D008665:Metalloporphyrins; D011524:Protoporphyrins; C017803:zinc protoporphyrin; D006427:Hemin; D014001:Tin; D005340:Fibrinogen; D005293:Ferritins; C032628:tin protoporphyrin IX; D007501:Iron