Purification and properties of RAT α2 acute-phase Macroglobulin (α2M): abstract
article
For our studies on the relation between blood fibrinolytic activity and repair of mechanically damaged arteries in our rat mode 1 we need a specific and sensitive assay for α2M, In the rat α2M is an acute-phase protein of which the level in blood is normally near zero but increases as a result of the damage. Moreover α2M is known to inhibit proteases involved in the fibrinolytic system. We developed a new purification procedure in which, conditions known to be harmful to the functionality of α2M were avoided. α2M was purified from plasma of turpentine-treated rats and proteolytic activities were suppressed throughout the purification procedure. The purification scheme successively involves: rivanol precipitation, Con A-Sepharose chromatography and DEAE-ce1 Iulose chromatography. Thusmg of α2M was obtained from 100 ml rat plasma i.e, 20% recovery. The preparations were biochemically and immunologically pure, Amino acid and carbohydrate compositions were determined. The molecular weight is 760.000, The molecule consists of 4 subunits, M.W. = 190.000. A 1% 1cm = 8.8 and pl = 4.8. It binds 1 mole of trypsin or plasmin per mole. Bound proteases were only active on low molecular weight substrates such as BAEE and BOC-L-va1-gIy-L-arg ßNA. Kinetic data of the bound enzymes (pH-optimas, Km and Vmax) indicate that factors other than steric hindrance are involved in the inhibitory act ion of α2M.
TNO Identifier
288925
Source
Thrombosis and haemostasis, 42, pp. 123.
Pages
123
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