Biol 1201 exam 1

Biol 1201 exam 1 - 1/27/09 Native and denatured proteins...

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1/27/09 Native and denatured proteins (fig. 5.23) Native – properly folded and functional Denatured – unfolded and doesn’t have Roles of Weak Bonds in Biological Systems (fig. 5.21) Are easily made an broken at physiological temperatures Provide specificity If “weak” interactions were “strong”, would crystallize the contents of a cell Attract and attach substrates to enzymes Determine molecular shape – a compromise between backbone and side groups Bonds responsible for primary structure: Peptide and Covalent Bonds responsible for secondary structure: Hydrogen H – bonding in 2 nd structure: Atoms in peptide backbone Freezing The freezing problems confronting fish Antifreeze peptides Small proteins (=peptides) that depress the freezing points of solutions Non-colligative freezing point depression A colligative properly depends on the number of dissolved molecules: True Colligative Properly
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Depends on the number of particles (molecules) and not on the nature of the molecules “Hysteresis proteins” – affect freezing point but not the melting point o Decrease the freezing point o Do not change the melting point o Freeze at -2 degrees C, melt at 0 degrees C Model of peptide hydrogen bonded to ice Growing Ice Crystal Mechanism of Inhibition of Crystal Growth Antifreeze peptides H-bond with ice Make it energetically more difficult to add a water molecule to the curved surface of the ice crystal. Temperature must be lowered to add the molecule Decreased freezing point Antifreeze peptides have what kind of structure? Helical ______ R groups H bond to the ice vCJD
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Early onset variant of CJD o From eating meat from infected cow o As of Jan. 5, 09 164 deaths in the UK, 3 cases still alive vCJD in US As of June 2008 3vCJD cases All epidemiologically linked to likely exposures to cattle products contaminated with BSE while residing in the UK and Saudi Arabia Kuru Laughing Disease Scrapie A disease in sheep Mad Cow Disease (BSE) Chronology in the UK In the 1970’s – mid 1980’s spread from sheep to cattle o Sheep meal and bones added to cattle feed 1982 Prusiner discovers prions 1986 Mad cow disease identified In 10 years 165,000 cattle affected November 1989 British Government banned use of animal derived feed supplements March 3, 1996 EU bans British beef Banned feed Sold in Europe and Asia
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Sold for “use” in poultry vCJD in Great Britain and France o All but one vCJD patients younger than 40 yrs. Old Unusual diseases Not caused by “germs” Not a virus, bacteria, or fungus Not caused by organism with genetic material! Prions (fig. 19.11)
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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Biol 1201 exam 1 - 1/27/09 Native and denatured proteins...

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