课程名称︰生物化学 课程性质︰化学系大三大四 五选三必修 课程教师︰陈平副教授 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰2012 03 07 考试时限（分钟）：50min 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Name(1pt):_____________ 学号(1PT):_____________ (Total 101pts, maximum 101 pts) I Multiple Choice(8x4 pts; 32pts; there is only one correct answer) 1.Which amino acids contain sulfur? A) serine and methionine B) serine and threonine C) methionine and threonine D) cysteine and methionine E) cysteine and threonine 2.The most likely total charge of peptide H-Phe-Asn-Glu-Tyr-Arg-Trp-His-OH at pH7 is A) +2 B) +1 C) 0 D) -1 E) none of the above 3.Tn the peptide Phe-Ala-Gly-Arg, which amino acid is the C-terminus? A) Ala B) Phe C) Phe and Arg D) Arg E) none of the above 4.The average molecular weight of the 20 standard amino acids is 138, but biochemists use 110 when estimating the molecular weight of a protein. Why? A) 110 accounts for the relatively small size of nonstandard amino acids. B) 110 reflects the higher proportion of small amino acids in proteins, as well as the loss of water when the peptide bond forms. C) 110 is based in the fact that the average molecular weight of protein is 110000 wuth an average of 1000 amino acids. D) 138 represents the molecular weight of conjugated amino acids. E) 110 reflects the number of amino acids found in the typical small protein, and only small proteins have their molecular weight estimated this way. 5.Why is the peptide bond planar? A) hydrogen bonding between the NH and C=O groups limits movements. B) bulky side chains prevent free rotation around the bond. C) ut contains partial double bond character, preventing rotation. D) None of the above. E) All of the above. 6. The primary angles of rotation considered in protein backbones are A) ψ and ω B) φ and ω C) ψ and φ D) α and ω E) α and φ 7. The spatial arrangement of protein chains is called A) quaternary structure B) tertiary structure C) secondary structure D) primary structure D) none of the above 8. Arrangements of amino acid residues thet are local recurring structures? A) primary structure B) secondary structure C) tertiary structure D) quaternary structure D) none of the above II Fill in the blanks( 4x4 pts; 16 pts total) 1. Which noncovalent interactions are driving force for protein folding? 1)____________________ 2)____________________ 3)____________________ 4)____________________ III Curve Drawing. Please draw the unfolding curve for the protein as described below. (2x3 pts; total 6 pts) (y-axis:Fraction Unfolded; x-axis:temperature) 1.More stable than protein A with 2.Same Tm as protein A, but higher similar cooperativity compared in cooperativity than protein A to protein A | ---- | ---- | ／ | ／ | / | / | / | / | | | | | | | | | / | / | / | / | ／ | 　／ | ---- | ---- |___________________ |____________________ IV Ramachandran diagrams. (2x3 pts; total 6pts) 1.Please indicate the region for the α-helix. _________________________ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　 　｜ ｜　　　　　｜　　 ｜ ｜ ｜ ｜ ├----------┼-----------┤ ｜　　　　　｜　　　　 ｜ ｜　　　　　｜　　　 ｜ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　 ｜ ｜　　　　　｜　　 　　　｜ └----------┴-----------┘ 2.Please indicate the region for the β-sheet _________________________ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　 　｜ ｜　　　　　｜　　 ｜ ｜ ｜ ｜ ├----------┼-----------┤ ｜　　　　　｜　　　　 ｜ ｜　　　　　｜　　　 ｜ ｜　　　　　｜　　　　　 ｜ ｜　　　　　｜　 ｜ ｜　　　　　｜　　 　　　｜ └----------┴-----------┘ V Amino acid Names. Write the one letter code for the following peptide represented in three letter code. (15 pts) Trp-Glu-His-Ala-Asp-Ala-Gly-Arg-Clu-Ala-Thr-Gly-Ala-Met-Glu VI Amino Acid Structures (24pts) 1. Name the two acids that have two chiral centers each. Give their one and three letter codes and draw their chemical structure. (name, 2x1 pts; codes 2x2x1 pts; structure 2x3 pts; stereoconters 2x2x1 pts; total 16pts) 2. Draw the chemical structures for Trp and His (structure 2x3 pts; stereocenters 2x1 pts; total 8pts) (参考解答) I DCDBCCAB II H-bond hydrophobic interaction Van der Waal force electrostatics interaction III 1.整条曲线往右移 2.曲线不动 中间变陡 IV 1.第三象限 2.第二象限 V WEHADAGREATGAME (居然有暗藏玄机= =) VI (结构略) 1.Isoleucine Ile I & Threonine Thr T 2.(略) --

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