<prompt> Heparin inhibits Xa byBlocking vitamin K mediated activation of XaActivating Antithrombin IIIDirect breakdown of XaBlocking P2 Y12 receptor of ADP  <response>: Heparin contains pentasaccharide unit that activates Antithrombin III inhibits factor Xa Thus it is a indirect thrombin inhibitor.Unfractionised heparin also contains a heteropolysaccharide unit that inhibits factor II a.LMWH lacks this heteropolysacchoride unit and therefore inhibitors factor Xa only. 