TAILIEUCHUNG - Báo cáo khoa học: Cold survival in freeze-intolerant insects The structure and function of b-helical antifreeze proteins

Antifreeze proteins (AFPs) designate a class of proteins that are able tobind toand inhibit the growthofmacromolecular ice. These proteins have been characterized froma variety of organisms. Recently, the structures ofAFPs fromthe spruce budworm (Choristoneura fumiferana) and the yellow meal-worm (Tenebrio molitor) have been determined by NMR and X-ray crystallography. Despite nonhomologous sequences, both proteins were shown to consist ofb-helices. We review the structures and dynamics data of these two insect AFPs to bring insight into the structure–function relationship and explore theirb-helical architecture | Eur. J. Biochem. 271 3285-3296 2004 FEBS 2004 doi REVIEW ARTICLE Cold survival in freeze-intolerant insects The structure and function of p-helical antifreeze proteins Steffen P. Graether and Brian D. Sykes CIHR Group in Protein Structure and Function Department of Biochemistry and Protein Engineering Network of Centres of Excellence University of Alberta Edmonton Alberta Canada Antifreeze proteins AFPs designate a class of proteins that are able to bind to and inhibit the growth of macromolecular ice. These proteins have been characterized from a variety of organisms. Recently the structures of AFPs from the spruce budworm Choristoneura fumiferana and the yellow mealworm Tenebrio molitor have been determined by NMR and X-ray crystallography. Despite nonhomologous sequences both proteins were shown to consist of b-helices. We review the structures and dynamics data of these two insect AFPs to bring insight into the structure-function relationship and explore their b-helical architecture. For the spruce budworm protein the fold is a left-handed b-helix with 15 residues per coil. The Tenebrio molitor protein consists of a right-handed b-helix with 12 residues per coil. Mutagenesis and structural studies show that the insect AFPs present a highly rigid array of threonine residues and bound water molecules that can effectively mimic the ice lattice. Comparisons of the newly determined ryegrass and carrot AFP sequences have led to models suggesting that they might also consist of b-helices and indicate that the b-helix might be used as an AFP structural motif in nonfish organisms. Keywords antifreeze protein beta-helix dynamics ice insect NMR structure thermal hysteresis water X-ray crystallography. Introduction Several organisms are freeze-intolerant yet are able to survive subzero temperatures by decreasing the probability of ice nucleation in their bodies. Survival strategies include the removal of water from areas that may come in .

• Báo cáo khoa học
• Report medicine
• traditional medicine
• scientific reports
• biochemical studies
• environmental medicine
• Crystal structure
• medical knowledge
• medical research
• analysis of cytoplasmic
• oxidation
• bacteria
• hemoglobin
• medicine
• cell proliferation
• breast cancer
• chemical reaction
• gastric cancer
• hormone medicine
• tumor cells