13 - Friday Lecture 13 Announcements 1 Quiz 3 results a...

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Friday, September 23, 2011, Lecture 13 Announcements: 1. Quiz 3 results: a 25.4 sd 3.7 b 25.7 sd 3.3 c 25.1 sd 3.8 2. Meet today at 2:55PM in Comstock B108: “Applying to graduate school-- what are they looking for?" 3. Like to write? Want to work on issues of health or health policy? Contact Susan Duan at ZD32. First meeting will be Tuesday evening 9/27 at 5:30PM, room TBA. Wednesday's lecture: Ion pairs stabilize the structure of deoxy-Hb. These are “potential” ion pairs, and by use of the Henderson-Hasselbalch equation, the fraction actually in an ion pair can be calculated. Quarternary structure (IV) of Hb can be in two states, R (relaxed) or T (tense) Bohr effect, fetal Hb getting oxygen from the mother, these are explained by ion pairs stabilizing the T-State Two models can explain Hb behavior: the Sequential Model and the 2-State Model. The 2-state model (i.e. R < -- > T ) is so successful that we will use only this one in the rest of the course. Today: ENZYMES LG p. 97 is a more clear and detailed version of Table 6-3 in your text. The 6 classes of enzymes describe ALL enzymes (!). 1 . Oxidoreductases: in the second column, you see EC1.1.1.1. EC stands for Enzyme Commission, the official organization that classifies enzymes. Each number after “EC” has a different meaning. The first number informs as to which of the 6 enzyme classes the enzyme belongs. A 1 means the enzyme is an oxidoreductase. In case this is useful for you (e.g. hunting for a particular enzyme), the web site that has the latest official nomenclature is: http://www.chem.qmul.ac.uk/iubmb/enzyme/index.html The second “1” means it uses a C-OH as electron donor. The third “1” means that NAD + or NADP + is the electron acceptor. (1.1.2 means a cytochrome is the electron acceptor; 1.1.3 means oxygen is the electron acceptor) The last “1” indicates substrate specificity, i.e. the specific enzyme 2 . Transferases: These enzymes catalyze the transfer or functional groups. 2.7 means a transfer of a phosphate.
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2.7.1 means an -OH is accepting the phosphate. (So, 2.7.1 is a general description for kinases) indicates the last level of substrate specificity, for glucose 3 . Hydrolases: These enzymes catalyze water addition across a bond. Also in this category are the membrane transporters! For example: 3.6 means “acting on acid anhydride” with 3.6.4 acting on ATP, 3.6.5 acting on GTP, and 3.6.3 acting on ATP or GTP and causing movement of another molecule across a membrane . Carboxypeptidase and trypsin are also examples of hydrolases. 4 . Lyases: These enzymes catalyze the removal or addition of a “group” usually at double bonded atoms, such as at C=C, or C=O, or C=N (but hydrolysis is not involved in the rxn) .
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13 - Friday Lecture 13 Announcements 1 Quiz 3 results a...

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