The most potent IRI from this study is also capable of protecting frozen RBCs against the large temperature fluctuations associated with transient warming.Īntifreeze proteins and ice‐binding proteins have been discovered in a diverse range of extremophiles and have the ability to modulate the growth and formation of ice crystals. These compounds are capable of reducing the average ice crystal size of extracellular ice relative to a 15% glycerol control validating the positive correlation between a reduction in ice crystal size and increased post-thaw recovery of RBCs. We have identified several low molecular mass ice recrystallization inhibitors (IRIs) that are effective cryoprotectants for human RBCs, resulting in 70–80% intact RBCs using only 15% glycerol and slow freezing rates. RBC units frozen under these conditions must be subjected to a time-consuming deglycerolization process after thawing in order to remove the glycerol to <1% prior to transfusion thus limiting the use of frozen RBC units in emergency situations. In North America, cryopreservation of human red blood cells (RBCs) utilizes high concentrations of glycerol. Conventional cryoprotectants such as dimethyl sulfoxide (DMSO) and glycerol function by a number of different mechanisms but do not mitigate or control ice recrystallization at concentrations utilized in cryopreservation procedures. Here, the authors report a protocol for the synthesis of vinyl C-glycosyl amino acids and peptides, via a Ni-catalyzed reductive hydroglycosylation reaction of alkyne derivatives of amino acids and peptides with glycosyl bromides.ĭuring cryopreservation, ice recrystallization is a major cause of cellular damage. C-Glycosyl peptides/proteins are metabolically stable mimics of the native glycopeptides/proteins of great therapeutic potential, but their chemical synthesis is challenging. The resultant vinyl C-glycosyl amino acids and peptides, which bear common O/N-protecting groups, are amenable to further transformations, including elongation of the peptide and saccharide chains. It accommodates a wide scope of the coupling partners, including complex oligosaccharide and peptide substrates. Herein, we disclose a protocol for the syntheses of vinyl C-glycosyl amino acids and peptides, employing a nickel-catalyzed reductive hydroglycosylation reaction of alkyne derivatives of amino acids and peptides with common glycosyl bromides.
This chapter describes the studies on the use of AFPs in food, as well as the dietary sources of these proteins, their use in foods, their toxicity, and the factors that influence their use.Ĭ-Glycosyl peptides/proteins are metabolically stable mimics of the native glycopeptides/proteins bearing O/N-glycosidic linkages, and are thus of great therapeutical potential. However, in the future commercial use of these proteins will most likely be influenced by various factors such as isolation and purification, thermal stability, price, chemical synthesis, and development in molecular biology. There are many research results about the successful application of AFPs in the freezing and thawing of food. Initially the use of AFPs was limited to ice cream products, but now meat, frozen dough, fruit, and vegetables are also among the products investigated. Antifreeze proteins can halt the formation of large ice crystals associated with recrystallization during frozen storage and thawing, and their potential as a food additive have been investigated in the recent years. These compounds were first identified in 1969 by DeVries in the blood of fishes living in frozen sea areas and were named antifreeze proteins because they lowered the freezing point of the fish’s blood below the freezing point of sea water without significantly increasing the osmotic pressure. Antifreeze proteins (AFPs) are polypeptides produced by plants, animals, and microorganisms that allow them to survive at temperatures below zero.
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