quiz 2 2009

quiz 2 2009 - BIOCH 460 Feb 25, 2009 NAME (printed...

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BIOCH 460 Feb 25, 2009 NAME (printed LEGIBLY!) QUIZ #2A ( 20 pts) CIRCLE ONLY 1 ANSWER PER QUESTION. (3 pts) Which of the following is true about general acid-base catalysis? A. It requires the ions of water. B. Amino acid side chains on enzymes can act as proton donors or acceptors. C. It often involves covalent bonds formed between a metal ion and the substrate. D. It involves a transient covalent bond between the enzyme and the substrate General acid-base catalysis refers to proton transfers mediated by molecules other than water. These molecules can be weak organic acids or bases to serve as proton donors or acceptors, respectively. Alternatively, amino acid side chains on enzymes can act as proton donors or acceptors (3pts) In this enzyme mechanism, GLU35 is acting as a: A. nucleophile B. electrophile C. general acid D. general base GLU 35 acts as a general base catalyst to facilitate the attack of water, displacing Asp52 and generating product. (3 pts) You have isolated a new protease that cleaves peptide bonds following Asp and Glu. Based on its
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