Digestion of Proteins by Proteases
Proteases (also known as proteinases or peptidases ) hydrolyze the peptide bond between amino acid residues in a polypeptide chain. Proteases may be specific and limited to one or more sites within a protein, or they may be nonspecific, digesting proteins into individual amino acids. The ability to digest a protein at specific points is […]
Westren Blotting of Proteins
Often researchers will use Western blotting to identify proteins. Western blots rely on having an antibody to the protein. Antibodies are extremely specific and will bind only to one target protein. The first step is to separate the proteins by size by either standard SDS-PAGE or 2D-PAGE. The proteins are then transferred from the gel […]
Gel Electrophoresis OF Proteins
Studying proteins requires the ability to isolate and identify the proteins in a particular sample. The first step is to separate them. Much as electrophoresis on agarose gels is used to separate DNA by size, so polyacrylamide gel electrophoresis (PAGE) is used to separate proteins by size. Polyacrylamide has smaller pores than agarose and is […]
Proteomics
Today we have the genome sequences for humans as well as many other animals, plants, fungi, and bacteria. All these data have given scientists a global view of the various genes in humans and others. However, genes are only the first step to understanding how an organism works. Genes are transcribed into mRNA and then […]
Immune Memory and Vaccination
Individuals who survive an infection normally become immune to that particular disease, although not to other diseases. This is because the immune system “remembers” foreign antigens, a process called immune memory . Next time the same antigen appears, it triggers a far swifter and more aggressive response than before. Consequently, the invading microorganisms will usually […]
Monoclonal Antibodies For Clinical Use
There are many clinical uses for antibodies. They are used in diagnostic procedures (including the ELISA), for pregnancy testing, and to detect the presence of proteins characteristic of particular disease-causing agents. In the future, they may be used to specifically kill cancer cells or destroy viruses. Such uses need relatively large amounts of […]
Structure and Function of Immunoglobulins
Depending on the type of heavy chain, antibodies are categorized into different classes, and assume different roles in the immune system. The most abundant and typical antibody has a gamma heavy chain and is called immunoglobulin G (IgG) . IgG has four different subclasses, but as a whole, IgG is found mainly in blood serum. […]
Antibody Structure
Each antibody consists of four protein subunits, two light chains and two heavy chains , arranged in a Y-shape. Disulfide bonds between cysteine amino acid residues hold the chains together. Each of the light and heavy chains consists of a constant region and a variable region . The constant region is the same for all […]
The Great Diversity of Antibodies
Antibodies are proteins that recognize and bind to alien molecules. Because there are an almost infinite variety of possible alien molecules, a correspondingly vast number of different antibody molecules are needed. The amino acids making up protein molecules can certainly be arranged to give an almost infinite number of different sequences and, therefore, of different […]
Antibodies, Antigens, and Epitopes
Antigen The term antigen refers to any foreign molecule that provokes a response by the immune system. In practice, most antigens are proteins made by invading bacteria or viruses. In particular, glycoproteins, which carry carbohydrate residues, and lipoproteins, which carry lipid residues, generate strong immune responses, that is, they are highly antigenic. Other macromolecules can also […]