2011浙大考研本科生物化学课件SUMMARY1.ppt

Molecular chaperones; are proteins that interact with partially folded or improperly folded polypeptides, facilitating correct folding pathways or providing microenvironments in which folding can occur (heat shock protein). Chaperonins; are elaborate protein complexes required for the folding of a number of cellular proteins that do not fold spontaneously. Ligand; A molecule bound reversibly by a protein is called a ligand. Binding site; A ligand binds at a site on the protein, which is complementary to the ligand in size, shape, charge and hydrophobic or hydrophilic character. Induced fit; The binding of a protein and ligand is often coupled to a conformational change in the protein that makes the binding site more complementary to the ligand, permitting tighter binding. This structural adaptation is called induced fit. Substrate; The molecule acted upon by enzyme is called to be reaction substrate. Antibodies (immunoglobulins, Ig); The proteins at the heart of the humoral immune response are soluble and bind bacteria, viruses, or large molecules identified as foreign and target them for destruction. Ig are produced by B lymphocytes and making up 20% of blood protein. Immunoglobulin G (IgG) is the marjor class of antibody molecule and one of the most abundant proteins in the blood serum. IgG has four polypeptide chains: two large ones, called heavy chains, and two light chains, linked by noncovalent and disulfide bonds into a complex of Mr 150,000. Antigen; Any molecule or pathogen capable of eliciting an immune response is called antigen. An antigen may be a virus, a bacteria cell wall, or an individual protein or other macromolecule (Mr 5,000). Polyclonal antibodies; are those produced by many different B clles responding to one antigen, such as a protein injected into an animal. Cell in the population of B cells produce antibodies that bind specific, different epitopes within the antigen. Thus, polyclonal preparations contain a mixture of antibodies that