title: The relationship of structure and function in human Hageman factor. The association of enzymatic and binding activities with separate regions of the molecule.
abstract: Three regions of the human Hageman factor molecule termed the c, d, and e regions have been defined. Division of the molecule into these three regions is based on the analysis of fragments obtained by enzymatic cleavage during fluid-phase activation. The three regions have the following properties: (a) the c region has a mol wt of 40,000, has the capacity to bind to negatively charged surfaces, and does not have detectable enzymatic activity; (b) the e region possess a mol wt of 28,000 has enzymatic activity, and does not bind to negatively charged surfaces; (c) the d region has a mol wt of 12,000, is located between the c and e fragments but has not been detected as a freely existing polypeptide, and can bind firmly to negatively charged surfaces. The preparation of antibodies specific for the c and e regions is described as well as their use in defining the electrophoretic characteristics of the cde, cd, de, c, and e polypeptide fragments of Hageman factor. Evidence is given showing that the e region, but not the c or d, is released from a negatively charged surface when bound Hageman factor is exposed to proteolytic enzymes or whole plasma and that when this occurs in the presence of normal plasma, the e fragment becomes bound to C1 esterase inhibitor.
mesh_terms: D004586:Electrophoresis; D005174:Factor XII / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007122:Immunoelectrophoresis; D007457:Iodine Radioisotopes; D007610:Kallikreins / Q000494:pharmacology; D007616:Kaolin / Q000378:metabolism; D008970:Molecular Weight; D011288:Prekallikrein / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D007457:Iodine Radioisotopes; D007616:Kaolin; D005174:Factor XII; D011288:Prekallikrein; D007610:Kallikreins