C1q is purified from pooled normal human plasma. C1q separated from C1r and C1s and from other stabilizing proteins tends to aggregate easily. Because it was isolated and studied in numerous research laboratories, many buffers have been used to stabilize concentrated C1q and prevent aggregation. This product is presented as In 10 mM HEPES, 300 mM NaCl pH 7.2, 40% glycerol.
The protein concentration is of C1q; C1q has an extinction coefficient of E1%/280nm = 6.8. The functional activity is C1q activity in NHS on a mg/mg basis.
This product is native, human C1q complement component. Glycoprotein composed of 18 polypeptide chains consisting of three nonidentical subunits, A, B, and C, of M.W. 29 kDa, 26 kDa, and 19 kDa, respectively. Present in normal human serum at 70 µg/ml. Found in circulating blood plasma complexed with two C1r and two C1s molecules to form the first component of complement (C1). Activation of complement via classical pathway is triggered by binding of C1q to immune complexes containing IgG or IgM or to a variety of other activating substances, including C-reactive protein, retroviruses, and mitochondria. Subsequent to C1q binding, C1r and C1s are converted to proteolytic enzymes that are responsible for continuation of activation via the classical pathway. This product is tested for purity but not for C1r and C1s content.