Molecular weight of human high-molecular-weight kininogen light chain by equilibrium sedimentation in an air-driven ultracentrifuge.
High-molecular-weight kininogen, a nonenzymatic glycoprotein of the intrinsic blood coagulation system, is proteolytically cleaved by kallikrein as an early event in the activation of this system. The light chain of cleaved kininogen retains the ability to form specific noncovalent complexes with prekallikrein and factor XI, other members of this system. We have determined the molecular weight of human kininogen light chain by equilibrium sedimentation in buffers of differing density, using an air-driven benchtop ultracentrifuge. The resulting molecular weight (30,500 +/- 800 g/mol) and partial specific volume (0.660 +/- 0.008 ml/g) are consistent with the idea that a sizeable fraction of the carbohydrate of high-molecular-weight kininogen is associated with the light chain. This level of precision is relatively easy to attain. The procedures are detailed, along with expressions for error propagation, to permit ready application of the technique.
D000388:Air; D006801:Humans; D007704:Kininogens; D008433:Mathematics; D008970:Molecular Weight; D013050:Spectrometry, Fluorescence; D014461:Ultracentrifugation / Q000379:methods
D007704:Kininogens