Aggregated protein, macromolecular

Another complex macromolecular aggregate that can reassemble from its components is the bacterial ribosome. These ribosomes are composed of 55 different proteins and by 3 different RNA molecules, and if the individual components are incubated under appropriate conditions in a test tube, they spontaneously form the original structure (Alberts et al., 1989). It is also known that even certain viruses, e.g., tobacco mosaic virus, can reassemble from the components this virus consists of a single RNA molecule contained in a protein coat composed by an array of identical protein subunits. Infective virus particles can self-assemble in a test tube from the purified components. 

At the macromolecular level, adsorption of clay particles to biological molecules such as proteins reduces their rate of decomposition by protecting them from microbial attack (Jenkinson 1981). On a larger scale, entrapment of organic matter in soil aggregates reduces the rate of decomposition at least while the aggregate persists. On a soil-profile scale, Shields and Paul (1973) showed that the rate of decay of organic matter on the soil surface was... 

The events leading to the macromolecular associations observed with (3-lactoglobulin appear to be mediated by disulfide interactions. The initial solution proposed to reduce thermoinduced aggregation was to remove the Cys 121 and replace it with alanine (Cho et al., 1994). Unfortunately, recombinant protein could not be purified from inclusion bodies. The alternative... 

Cholesterol and triacylglycerols are transported in body fluids in the form of lipoprotein particles. Each particle consists of a core of hydrophobic lipids surrounded by a shell of more polar lipids and apoproteins. The protein components of these macromolecular aggregates have two roles they solubilize hydrophobic lipids and contain cell-targeting signals. Lipoprotein particles are classified according to increasing density (Table 26.1) chylomicrons, chylomicron remnants, very low density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Ten principal apoproteins have been isolated and characterized. They are synthesized and secreted by the liver and the intestine. 

The term macromolecule refers to a variety of compounds, including biologically important compounds such as proteins, nucleic acids, and also many important manmade polymers. They may further aggregate into what are called macromolecular assemblies. The molecular shapes of these compounds, because of their large size, have greater variability and are somewhat different from those of smaller compounds. Their possible conformations are an important component of their biological and chemical function. 

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