Endogenous heparinase-sensitive anticoagulant activity in human plasma

Area of Science:

• Biochemistry
• Hematology

Background:

• Human plasma contains anticoagulant factors.
• Heparin is a crucial anticoagulant, but its presence and isolation from plasma are challenging.

Purpose of the Study:

• To investigate the nature of anticoagulant activity appearing in human plasma after proteolytic digestion.
• To determine if this activity can be identified as heparin and explore reasons for its difficult isolation.

Main Methods:

• Proteolytic digestion of human plasma.
• Assay of anticoagulant activity using thrombin time.
• Enzymatic digestion with chondroitin ABC lyase, heparan sulfate lyase, and heparin lyase.
• Nitrous acid treatment.
• Ion-exchange chromatography on DEAE-Sephacel.

Main Results:

• An anticoagulant activity, measurable by thrombin time, emerged after plasma digestion.
• The activity exhibited heat stability and resistance to specific lyases, but sensitivity to heparin lyase and nitrous acid, suggesting it is heparin.
• The concentration was estimated at 0.1-0.2 I.U./mL in healthy subjects.
• Chromatography showed the activity eluting at low ionic strength.

Conclusions:

• The study identifies authentic heparin in human plasma following proteolytic digestion.
• The elution profile suggests heparin interacts with other plasma components, potentially proteins or protein fragments, complicating its isolation.