a2-Macroglobulin

Alpha2 Macroglobulin (a-2M) is a large proteinase inhibitor molecule of 718kD, consisting of 4 identical subunits of 185,000 each. It is produced in hepatocytes and macrophages, and generally found in plasma concentrations of 2uM in adults, and up to 6uM in children. a-2M inhibits most enzymes from the serine, metallo, cysteine and aspartate subclasses. It is classed with proteins that include pregnancy zone protein (PZP) and the complement proteins C3, C4 and C5. These proteins contain regions of conserved sequence as well as one or more internal b-cysteinyl-g-glutamyl thiolester bonds. In a-2M, these regions are susceptible to cleavage by enzymes or by nucleophilic compounds such as methylamine or ammonium ions. It is thought that enzymatic cleavage of a bait region within the a-2M molecule causes a conformational change, which then traps and/or covalently binds the enzyme (1,2). The active site of the trapped enzyme is usually still intact and able to cleave small substrates, but is inaccessible to larger natural substrates. The conformational change also exposes receptor-binding regions within the molecule, which may be important in the clearance of a-2M enzyme complexes from the circulation. It is thought that the main role of a-2M in vivo is

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SPECIFICATIONS

Catalog Number

M1150-20A

Size

1mg

Applications

ELISA

Hosts

Goat

Reactivities

Hum, Can, Prc, Rabbit

Form

Supplied as a liquid in 0.01M HEPES, pH 7.4, 0.1M sodium chloride, 50% glycerol.

P Type

Pab

Purity

Purified by caprylic acid and ammonium sulfate precipitations, and solid -phase adsorption to remove unwanted crossreactivity.

Isotype

IgG

References

1. Salvesen G, Pizzo SV; Proteinase Inhibitors: a-Macroglobulins, Serpins and Kunins; in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp. 241-258, J.B. Lippincott Co., Philadelphia PA, USA, 1994. 2. Barrett J; a-2Macroglobulin; Methods in Enzymology, 80, pp 737-754, 1981 Larsson LJ, Neuenschwander DE, Strickland DK; Reaction of Proteinases with a-2Macroglobulin: Evidence for Alternate Reaction Pathways in the Inhibition of Trypsin; Biochemistry 28, pp 7636-7643, 1989. 3. Schmidt B, Mitchell L, Ofosu FA, Andrew M; a-2Macroglobulin is an Important Progressive Inhibitor of Thrombin in Neonatal and Infant Plasma; Thromb Haemostas 62, pp 1074-1077, 1989. 4. Hoogendoorn H, Toh CH, Nesheim ME, Giles AR; a-2Macroglobulin Binds and Inhibits Activated Protein C; Blood 78, pp2283-2290, 1991.

Additional Info

Recognizes Macroglobulin, alpha2.\nSpecies crossreactivity: Human, rabbit, porcine and canine.