Antibodies globular proteins

Solution pH has a strong influence on the structure, conformation and solubility of globular proteins. However, when IgO, antibody was added to fresh, sterile B5 medium adjusted to pH values between 4.0 and 8.0, there was no significant difference in the rate at which the antibody disappeared from the different solutions [63]. In other work, antibody-expressing tobacco hairy roots were cultured in B5 medium with initial pH between 3.0 and 11.0 [69]. Root growth was affected severely at the lowest and highest pH values and total antibody levels declined as the initial pH was increased above 5.0-6.0. 

Enzyme is a globular protein with an active site which binds to substrate molecules and helps to catalyze a reaction by holding melecules in the correct spatial conformation for the reaction to take place. Enzymes are important to health many diseases are derived fron the lack of enzymes in the body. In enzyme-histochemical chromogenic reactions, a soluble colorless substrate is converted into a water-insoluble colored compound either directly or in a coupled reaction. In immunohistochemistry, enzyme labels are usually coupled to antibodies or to (strept)avidin. 

In sharp contrast, the shape of globular proteins is spherical or ellipsoidal. They are soluble in water and their solutions have low viscosities (see Chapter 6). They find use as transport agents, enzymes, antibodies, and some hormones. The chains in globular proteins are extensively folded and usually contain both helical and nonhelical segments. 

Epitope The structural part of an antigen that reacts with an antibody. These are groupings of amino acids in globular proteins and sugar side-chains in polysaccharides. The most critical part is called the immunodominant point. 

The performance of protein or antibody microarrays is dependent on various factors. One of these is the use of an appropriate microarray surface for the immobilization of the protein or antibody samples. Most conventional microarray surfaces have been adapted from DNA chip technology. DNA can easily be immobilized by electrostatic interactions of the phosphate backbone onto a positively charged surface. In contrast to DNA, as already mentioned, proteins are chemically and structurally much more complex and show variable charges, which may influence the efficiency of protein attachment. Additionally, proteins lose their structure and biochemical activity easily. For example, globular proteins consist of a hydrophilic exterior and a hydrophobic interior. When immobilized on a hydrophobic surface, the inside of the protein turns out, which may destabilize the structure and, simultaneously, the activity of the protein. These considerations demonstrate the complex requirements for protein immobilization. 

Based on size and shape, the proteins are also subdivided into globular and fibrous proteins. Globular proteins are mostly water-soluble and fragile in nature. Example- enzymes, hormones and antibodies. Fibrous proteins are tough and water-insoluble. They are used to build a variety of materials that support and protect specific tissues. Example- Skin, Hair, Fingernails and Keratin. 

Immunoglobulin A class of globular proteins = antibody Ligand A member of a binding pair, generally the smaller member Matrix effect Any bias in the assay result... 

Antibodies, or immunoglobulins, are globular proteins with molecular weights of 150 to 200 kdal. They are made up of four subunits, two "heavy" and two "light" chains, which together form a "Y"-shaped molecule. The stem of the antibody is referred to as the "constant" or F region, while the two branches containing the... 

Fibrous proteins provide the structural material of many tissues in the body. They are the chief constituents of hair, cartilage, and muscles. Fibrous proteins consist of lengthwise bundles of polypeptide chains (a fiber). Globular proteins consist of polypeptide chains folded into a spherical shape they are found in the bloodstream where they transport and store various substances, act as antibodies (fight infections), act as enzymes (catalysts), and participate in the body s various regulatory systems. 

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