Proteins insolubilities

Scieroproteins. Insoluble proteins obtained from the skeletal and connective tissues of animals. Typical classes are keratins collagens and elastin classes. 

This is an extracellular deposition of an insoluble protein, which has adopted a (3-sheet structure due to an unknown event that induced misfolding of unstable proteins. The name amyloid has been given according to the amyloid staining properties, which are similar to carbohydrate deposits, e.g., amyloid can be identified with Congo red and seen under polarized light (birefringence test). 

Hemostasis is the process that stops bleeding in a blood vessel. Normal hemostasis involves a complex process of extrinsic and intrinsic factors. Figure 44-1 shows the coagulation pathway and factors involved. The copulation cascade is so named because as each factor is activated it acts as a catalyst that enhances the next reaction, with the net result being a large collection of fibrin that forms a plug in the vessel. Fibrin is the insoluble protein that is essential to clot formation. 

The first elastomeric protein is elastin, this structural protein is one of the main components of the extracellular matrix, which provides stmctural integrity to the tissues and organs of the body. This highly crosslinked and therefore insoluble protein is the essential element of elastic fibers, which induce elasticity to tissue of lung, skin, and arteries. In these fibers, elastin forms the internal core, which is interspersed with microfibrils [1,2]. Not only this biopolymer but also its precursor material, tropoelastin, have inspired materials scientists for many years. The most interesting characteristic of the precursor is its ability to self-assemble under physiological conditions, thereby demonstrating a lower critical solution temperature (LCST) behavior. This specific property has led to the development of a new class of synthetic polypeptides that mimic elastin in its composition and are therefore also known as elastin-like polypeptides (ELPs). 

The transmissible spongiform encephalopathies, or prion diseases, are fatal neurodegenerative diseases characterized by spongiform changes, astrocytic gliomas, and neuronal loss resulting from the deposition of insoluble protein aggregates in neural cells. They include Creutzfeldt-Jakob disease in humans, scrapie in... 

Fibrin An insoluble protein that is one of the principal ingredients of a blood clot. Fibrin strands bind to one another to form a fibrin mesh. The fibrin mesh often traps platelets and other blood cells. 

V. ANIMAL MODELS OF BRAIN DEPOSITION OF INSOLUBLE PROTEINS... 

Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Aarhus C 8000 Aarhus, Denmark e-mail ncn chem.au.dk... 

Amyloid fibrils are elongated, insoluble protein aggregates deposited in vivo in amyloid diseases, and amyloid-like fibrils are formed in vitro from soluble proteins. Both of these groups of fibrils, despite differences in the sequence and native structure of their component proteins, share common... 

After two fractionations between 0.33 and 0.6 saturated ammonium sulfate, several precipitations at 0.6 saturation were made throughout a period of two or three days, during which the preparation was stored in the refrigerator. Any denatured, insoluble proteins were removed by centrifugation, and a solution of the desired activity was prepared by dilution with buffer or distilled water. 

On a larger scale, we have ligaments and cartilage, structures that hold joints together and tie muscle to bone. These too are composed of proteins tough, water-insoluble proteins. Principal among them are the collagens. 

Finally, we have other water-insoluble proteins that constitute such structures as skin, hair, the wool of sheep, fur in other animals, silk, kangaroo tail, and the like. 

Coiiagen a strong, insoluble protein that forms the organic component of bone. 

The delipidated serum lipoprotein proteins exhibit solubility differences in aqueous media. The polypeptides of HDL and the D polypeptides of VLDL are readily soluble in aqueous media, particularly in slightly alkaline low-ionic strength buffers (S28, S30). In contrast, the LDL protein does not dissolve in such buffers and, like many other water-insoluble proteins, requires denaturing agents, detergents, or suitable chemical modification. The many techniques for the solubilization of apo LDL have been reviewed recently (G15). A thorough assessment of such techniques is not possible since not all the solubilized products have been characterized. The choice of the method presently depends on the investigator s preference and experimental needs. 

Peptides consisting of residues from GroEL immobilized on agarose have proved effective minichaperones (Altamirano ef al., 1997). The procedure used both column chromatography and batch-wise methods to renature an insoluble protein from an inclusion body, refold apparently irreversibly denatured proteins, and to recondition enzymes that have lost activity on storage. Eragments were immobilized by two methods Ni-NTA resin and CNBr-activated Sepharose 4B. 

Alexandrov, A., Dutta, K. and Pascal, S. M. (2001). MBP fusion protein with a viral protease cleavage site one-step cleavage/purification of insoluble proteins. Biotechniques 30, 1194—1198. 

Waters, E. J., Peng, Z., Pocock, K. F., and Williams, P. J. (1995). Proteins in white wine, I Procyanidin occurrence in soluble proteins and insoluble protein hazes and its relationship to protein instability. Aust. ]. Grape Wine Res. 1, 86-93. 

Short-term ozone exposures (45 5 pphm, 15 min) of seedlings were followed after 24 hr by non-linear reductions in chlorophyll/g fresh weight and stimulations in fresh weight/organ. The utilization of l C-protein hydrolysate by tissue discs is not only predominantly energy-dependent, but also strictly dependent with respect to inhibition or stimulation upon the time after ozonation. Uptake of labelled amino acids into the soluble pools of tissue discs is sensitive to as little as 15 min of in vivo exposure (45 5 pphm), and incorporation into insoluble protein is sensitive during 15 to 30 min, after which no further reduction is observed for up to 90 min of exposure. The reduction of amino acid influx into the soluble pools is not accountable to a reduction in amino acid tRNA charging, and is probably not due to a reduction in amino acid incorporation. 

After centrifugation of the TCA/acetone extract, nonquenching aliquots of the supernatant were counted by liquid scintillation, and the pellet digested overnight in 2N NaOH. Counts present in the TCA/acetone supernatant were taken to represent the uptake of label into the soluble amino acid pool, while solubilized counts present in the NaOH digest were taken to represent incorporation into TCA-insoluble protein. 

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