- Name for a family of proteins precipitated from plasma (or serum) by half-saturation with ammonium sulfate ( i.e., addition of an equal volume of saturated ammonium sulfate). Globulins may be further fractionated by solubility, electrophoresis, ultracentrifugation, and other separation methods into many subgroups. The main groups are α-, β-, and γ-g., which contains most antibodies. [L. globulus, globule]- accelerator g. (AcG, ac-g) g. in serum that promotes the conversion of prothrombin to thrombin in the presence of thromboplastin and ionized calcium. See factor Va, factor V, serum accelerator g..- antihemophilic g. A SYN: factor VIII.- antihemophilic g. B SYN: factor IX.- antihuman g. serum from a rabbit or other animal previously immunized with purified human g. to prepare antibodies directed against human immunoglobulin, some of which may be used in the direct and indirect Coombs tests. SYN: Coombs serum.- antilymphocyte g. (ALG) SYN: antilymphocyte serum.- β1C g. g. fraction of serum that contains the third component (C3) of complement. See component of complement.- chickenpox immune g. (human) g. fraction of serum from persons recently recovered from herpes zoster infection; used to prevent infection of high-risk children. SYN: chickenpox immunoglobulin.- gonadal steroid-binding g. (GBG) a protein that transports 65% of the testosterone in plasma. SYN: sex steroid-binding g..- human gamma g. a preparation of the proteins of liquid human serum, containing the antibodies (primarily IgG) of normal adults; it is obtained from pooled liquid human serum from a number of donors and may be prepared by precipitation under controlled conditions of pH, ionic strength, and temperature. SYN: human normal immunoglobulin.- immune serum g. a sterile solution of globulins that contains many antibodies normally present in adult human blood; a passive immunizing agent frequently used for prophylaxis against hepatitis A and for treatment of Kawasaki disease, idiopathic thrombocytopenic purpura, and some immunodeficiencies.- measles immune g. (human) a sterile solution of globulins derived from the blood plasma of adult human donors with elevated titers to measles : it is prepared from immune serum g. that complies with the measles antibody reference standard; a passive immunizing agent. SYN: measles immunoglobulin.- pertussis immune g. a sterile solution of globulins derived from the plasma of adult human donors who have been immunized with pertussis vaccine; used both prophylactically and therapeutically. SYN: pertussis immunoglobulin.- poliomyelitis immune g. (human) a sterile solution of globulins that contains antibodies normally present in adult human blood with elevated titers to poliomyelitis and confers temporary but significant protection against paralytic polio. SYN: poliomyelitis immunoglobulin.- rabies immune g. (human) g. fraction of pooled plasma of high anti-rabies virus titer from immunized persons. SYN: rabies immunoglobulin.- RHo(D) immune g. a g. fraction of antibody, derived from human donors, specific for the most common antigen, Rho(D), of the Rh group; used to prevent Rh-sensitization of an Rh-negative woman after delivery of an Rh-positive fetus. SYN: anti- D immunoglobulin, Rho(D) immunoglobulin.- serum accelerator g. a substance in serum that accelerates the conversion of prothrombin to thrombin in the presence of thromboplastin and calcium; produced by the action of traces of thrombin upon plasma accelerator g..- sex hormone-binding g. (SHBG) a plasma β-g., produced by the liver, that binds testosterone and, with a weaker affinity, estrogen; serum levels of SHBG in women are twice the levels seen in men; serum concentrations are increased in certain types of liver disease and in hyperthyroidism but are decreased with advancing age, by androgens, and in hypothyroidism. SYN: testosterone-estrogen-binding g..- sex steroid-binding g. SYN: gonadal steroid-binding g..- specific immune g. (human) g. fraction of pooled serums (or plasma) selected for high titer of antibodies specific for a particular antigen, or from persons specifically immunized.- testosterone-estrogen-binding g. SYN: sex hormone-binding g..- tetanus immune g. a sterile solution of globulins derived from the blood plasma of adult human donors who have been immunized with tetanus toxoid; a passive immunizing agent. SYN: tetanus immunoglobulin.- thyroxine-binding g. (TBG) an α-g. of blood with a strong binding affinity for thyroxine; triiodothyronine is bound to it much less firmly; a deficiency or excess of this protein may occur as a rare benign X-linked disorder. SYN: thyroxine-binding protein (1).- zoster immune g. a g. fraction of pooled plasma from individuals who have recovered from herpes zoster; used prophylactically for immunosuppressed children exposed to varicella and therapeutically to ameliorate varicella infection.
* * *glob·u·lin 'gläb-yə-lən n any of a class of simple proteins (as myosin) that are insoluble in pure water but are soluble in dilute salt solutions and that occur widely in plant and animal tissues see ALPHA GLOBULIN, BETA GLOBULIN, GAMMA GLOBULIN
* * *n.one of a group of simple proteins that are soluble in dilute salt solutions and can be coagulated by heat. A range of different globulins is present in the blood (the serum globulins, including alpha (a), beta (b), and gammaglobulin). Some globulins have important functions as antibodies (see immunoglobulin); others are responsible for the transport of lipids, iron, or copper in the blood. See also hormone-binding globulins.
* * *glob·u·lin (globґu-lin) [L. globulus globule] any member of a class of proteins, most of which are insoluble in water but soluble in saline solutions (euglobulins), but some of which (pseudoglobulins) are water soluble proteins whose other physical properties closely resemble those of the true globulins. See also serum g's.
Medical dictionary. 2011.