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Unformatted text preview: __________________________________ _____________________________________ Name (Last, First) SOLAR ID 1 BIO 361 EXAM 1 FALL 2008 VERSION 1 NAME:_________________________________________________ ID:_____________________________________________________ 1. Write Your name and ID on all pages 2. Write all answers in pen only 3. Make sure your exam has five pages including this cover page Page 2 _______________ Page 3 _______________ Page 4 _______________ Page 5 _______________ Total _______________ __________________________________ _____________________________________ Name (Last, First) SOLAR ID 2 1-5. You have been given five samples of amino acids or peptides, but the labels have become detached from the samples. The labels are: a. Phe-Leu-Tyr b. Ser-Gly-Ser c. Hypro-Gly-Pro d. Asp e. Arg-Arg-Arg Indicate which of the labels listed could be reasonably applied to each sample described below. If none of the labels describes the sample, write NONE, and if more than one label could be applied, write the letters for each of the labels which could be applied (4 points each - points will be deducted if too many choices are given). 1. _____ This sample is fully titrated from an initially acidic solution of below pH 2 when five equivalents of a base are added per mole of sample. 2. _____ This sample could have been derived from tropocollagen. 3. _____ This sample is fully titrated from an initially acidic solution of below pH 2 when three equivalents of a strong base are added per mole of sample. 4. _____ This sample will emerge last from a column of sulfonated polystyrene when using a pH gradient to elute the materials. 5. _____ This sample will emerge first from a gel filtration column of phenyl sepharose in which a percentage of the hydroxyl groups of highly crosslinked Sephadex have been modified with phenyl substituents. 6-9. You have been given a sample from a new collection of linear octapeptides (8 linked amino acids). You first attempt to cleave the peptide with cyanogen bromide. Answer the following questions TRUE or FALSE (6, 7, 8 - 3 points each; please write out TRUE or FALSE completely, not T or F. 9. 4 points) 6. _____ If you obtain a dipeptide with a C-terminal homoserine lactone, the original peptide in your sample must have had a methionine adjacent to the N-terminal amino acid. 7 _____ If you obtain a dipeptide with no homoserine lactone, the original peptide in your sample must have had a methionine directly adjacent to the C-terminal amino acid. 8. _____ If you cannot cleave your sample octapeptide with cyanogen bromide, it must not contain methionine. 9. Your sample octapeptide contains one lysine and one methionine; it is cleaved rapidly by trypsin before treatment with cyanogen bromide but very slowly or not at all with trypsin after treatment with cyanogen bromide. The most likely explanation for this is that the following amino acid sequence exists within the octapeptide (-X-Y- indicates both X and Y are internal): a. Met-Lys- b. Lys-Met- c. Met-Lys-COOH d. -Lys-Met-COOH e. NH 2-Lys-Met-...
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This note was uploaded on 09/28/2009 for the course BIO 361 taught by Professor Lake during the Spring '08 term at SUNY Stony Brook.
- Spring '08