Cryoprotectant natural

Rudolph, A. S., and Crowe, J. H. (1985). Membrane stabilization during freezing The role of two natural cryoprotectants, trehalose and proline, Cryobiology, 22, 367-377. 

Most protein crystals are not grown from naturally cryoprotecting solvents (even when an alcohol is the precipitant, its concentration is usually well below that required to prevent freezing below — 50°C) and therefore must be transferred into such solvents before cryoenzymologi-... 

The experimental objective of the study was to obtain a series of stop-action photographs of ribonuclease A at work at atomic resolution. The strategy for such a program has been considered in detail by Fink and Petsko (1981), who treat such subjects as diffusional constraints and turnover rates, and in the preceding sections of this article. The ribonuclease reaction has a series of well-characterized, stable species which can be purchased, and crystals of the enzyme are large, well ordered, catalyt-ically active (Fink et al, 1984), and have as their natural mother liquor a cryoprotective solvent (Petsko, 1975). RNase thus represents the ideal system for a step-by-step analysis of an enzymatic catalytic pathway by the methods outlined above. 

The PEG could stabilize proteins by two different temperature-dependent mechanisms. At lower temperatures, it is preferentially excluded from the protein surface but has been shown to interact with the unfolded form of the protein at higher temperatures, given its amphipathic nature (57). Thus, at lower temperatures, it may protect proteins via the mechanism of preferential exclusion, but at higher temperatures possibly by reducing the number of productive collisions between unfolded molecules. PEG is also a cryoprotectant and has been employed in Recombinate, a lyophilized formulation of recombinant Antihemophilic Factor, which utilizes PEG 3350 at a concentration of 1.5mg/mL. The low-molecular weight liquid PEGs (PEG 300-600) can be contaminated with peroxides and cause protein oxidation. If used, the peroxide content in the raw material must be minimized and controlled throughout its shelf life. The same holds true for polysorbates (discussed below). 

Trehalose is a relatively new bulk sweetener with potential for use in soft drinks. It is a di-glucose sugar and it occurs in nature in shellfish and mushrooms, where it confers a degree of protection to plant and animal cells in conditions causing dehydration. This led to its use as a cryoprotectant in freeze-drying systems in the pharmaceutical industry. In food markets, its potential use is as a bulk sweetener. It is manufactured using the Hayashibara patented process using starch as a raw material. The process involves enzymatic conversion and crystallisation to the trehalose dehydrate crystal (LFRA, 2001). 

Saccharomyces cerevisiae WRP45073A1 survives freeze drying and yeast survival rates were dependent on the nature of the cryoprotectants 13.1 1.8%, 9.5 6.0%,... 

It is not known whether such natural cryoprotectants occur widely distributed among animal species. However, a relevant experiment was conducted with brain slices, from warm-adapted and hibernating hamsters, before and after freezing (92). Tissue slices from the hibernating hamster exhibited higher than normal oxygen consumption rates after freezing. This result did not occur with slices from the warm-adapted... 

Sultanbawa, Y. and Li-Chan, E.C.Y. 2001. Structural changes in natural actomyosin and surimi from ling cod (Ophiodon elongates) during frozen storage in the absence or presence of cryoprotectants. Journal of Agricultural and Food Chemistry 49 4716 725. 

The usefulness of undercooled water as a reaction medium has also been demonstrated in biochemical studies. Thus, the kinetics of biochemical reaction sequences can be sufficiently slowed down to become time resolved at subzero temperatures in the unfrozen state. Even more importantly, complex reaction pathways (mechanisms) are unaffected by undercooling, whereas the use of conventional cryoprotectants (glycerol, ethane diol, dimethylsulfoxide, etc.) alters the pathways, although not necessarily the nature of the end products. Finally, single cells or even cell clusters can be stored and kept intact for considerable periods in undercooled aqueous media. 

Meryman, H.T., Williams, R.J. and Douglas, M.St.J, (1977). Freezing injury from solution effects and its prevention by natural or artificial cryoprotection. Cryobiology, 14, 287-302. 

Arctic and Antarctic insects, fish, amphibians, and reptiles naturally produce cryoprotectants to minimize freezing damage during cold spells. Insects commonly use sugars or polyols (alcohols) as cryoprotectants. Arctic frogs use glucose, and Arctic salamanders produce glycerol in their livers for use as cryoprotectant. 

Abstract Sorbitol is a natural cryoprotectant for some organisms. In order to reveal the mechanism of a protection some organisms against low temperatures, we studied the interaction between sorbitol and phosphatidylcholine (PC) which is one of major component of cell membranes. Small-angle neutronscattering contrast variation method was used to characterize dihexanoyl-PC (dC(6)PC) micelles in the presence of sorbitol (2 M). As a result, the aggregation number for the dC(6)PC micelle and the volume per a single molecule in the micelle were estimated... 

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