Heterogeneity of rat skin heparin chains with high affinity for antithrombin.
Subfractions of 35S-labelled rat skin heparin proteoglycans with various degrees of high affinity for antithrombin were obtained by gradient elution from a column of antithrombin-agarose. Heparin chains released from the proteoglycan preparations by beta-elimination with alkali were re-fractionated on the same column. Proportions of chains with high affinity for antithrombin (HA-chains) ranged from 17% to 76%. These separations also revealed three overlapping subfractions of HA-chains. Their proportions varied in a manner consistent with a stepwise increase in the degree of affinity of HA-chains for antithrombin, this presumably being due to the biosynthesis of increasing numbers of antithrombin-binding sites per chain. The anticoagulant activity, with respect to thrombin neutralization, ranged from 32 units/mg to 287 units/mg. It is suggested that HA-chains may have from one to five or six antithrombin-binding sites. Thus the asymmetric distribution of these sites in rat skin heparin proteoglycans is much more marked than was realized from the earlier work of Horner & Young [(1982) J. Biol. Chem. 257, 8749-8754].
Horner
A A
AA
Department of Physiology, University of Toronto, Ontario, Canada.
D000818:Animals; D000990:Antithrombin III / Q000378:metabolism*; D001665:Binding Sites; D001777:Blood Coagulation / Q000187:drug effects; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D006493:Heparin / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011509:Proteoglycans / Q000302:isolation & purification; D051381:Rats; D012867:Skin / Q000378:metabolism*
D011509:Proteoglycans; D000990:Antithrombin III; D006493:Heparin