Proteins preservation

Recently, Vasilescu et al. demonstrated the use of formaldehyde to preserve protein interactions in vivo followed by immunoaffinity purification of a targeted complex, cross-link reversal via heating at 95°C, separation by SDS-PAGE, and identification of bands by LC-MS/MS.7 Tagwerker et al. utilized formaldehyde cross-linking in conjunction with a novel tag-based affinity purification method.36... 

HIC, like IEC, is performed under conditions that preserve protein shape and activity. It is used in preparative applications to obtain a selectivity complimentary to IEC and akin to RPLC but without the denaturing properties of the latter technique. Although HIC and RPLC share a mechanism based on hydro-phobic partitioning, the actual peak spacing and elution order of the two techniques can be different. This arises from the different hydrophobic contact points presented by the protein under native (HIC) and denaturing (RPLC) conditions. Although not widely used for analytical separations, HIC can be used to answer questions about accessible hydrophobic surface area that cannot be addressed by RPLC.44... 

Fixation Fixation is the process by which the protein of cells is denatured, or cross-linked, and preserved. Fixation in flow cytometry is used to inactivate hazardous biological material and also to preserve stained cells when there is not immediate access to a flow cytometer. Fixation is also important in preserving proteins before detergent permeabilization for intracellular staining. Formaldehyde is often the fixative of choice for flow cytometry because it preserves the forward and side scatter characteristics of cells (but does cause some increase in their autofluorescence). 

Only lysine residues on the exterior of the protein molecule are thought to react and these usually account for 40-60% of the total lysyl residues.29 Formalin does not precipitate proteins and only slightly precipitates other components of the cell it is also a good fixative for complex lipids but has no effect on neutral fats and neither preserves nor destroys adipose tissue. Formalin also traps carbohydrates because it preserves proteins so that they hold glycogen, which is otherwise readily leached from the cell. Another advantage of the compound is that it does not produce large bands that obscure the major bands associated with the macromolecules in tissue samples. Furthermore formalin is inexpensive and available in most laboratories. 

Acceptance of DDG and DDGS products as animal feed supplements is limited by the variable "quality" of DDG and DDGS among ethanol plants and the relatively low crude protein content (4). This variability is caused by differing amounts of residual starch and crude protein in DG products. Crude protein content depends in part on preserving protein during the drying step. A study conducted by the Department of Animal... 

Friedberg I, Margalit H (2002) Persistently conserved positions in structurally similar, sequence dissimilar proteins roles in preserving protein fold and function, Protein Sci, 11 350-360... 

A mixture of protease inhibitors, which is used to preserve protein integrity during the processing of samples for subsequent analysis. The term cocktail refers to a mixture of components. A protease inhibitor cocktail is composed of a broad spectrum of protease inhibitors and intends to inhibit the diverse proteolytic enzymes found in tissue extracts and biological fluids. See Pringle, J.R., Methods for avoiding proteolytic artifacts in studies with enzymes and other proteins from yeasts. Methods Cell Biol. 12, 149-184, 1975 Dmbin, D.G., Miller, K.G., and Botstein, D., Yeast... 

Considering chemical stability, even alterations at single amino acids or the peptide bond can be detrimental [6], Chemical reactions having an impact on protein stability include hydrolysis of the peptide bond, deamidation, oxidation, p-elimina-tion, isomerization, and disulfide bond breakage and formation. The extent to which they occur is mainly influenced by the temperature and pH value of the solution [24], Bearing in mind that proteins react sensitively to the above-mentioned environmental conditions, preparation procedures for protein pharmaceuticals have to be chosen very carefully to preserve protein integrity and functionality. 

The "Crotein" and "Nutrilan" products present the wide scope of animal protein hydrolysates produced by Croda and Henkel, respectively, for cosmetic use. Preserved protein hydrolysates, protein condensation products and special protein products of the Chemische Fabrik Grunau Henkel Group) compiled from [106] are presented in Table 1.8. 

Dietary amino acid adequacy is markedly influenced by energy balance. Sufficient energy intake must be provided in diets for patients with inherited metabolic diseases to preserve protein for synthesis and adequate growth. Throughout the lifespan sufficient energy must be supplied for weight maintenance. 

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