Chapter 2

1. (a) tropomyosin原肌球蛋白 70-kd→ 35-kd (two-stranded)→ 318 residues

(mean residue mass 110)→ 477?(axial distance of per residue in α-helix is 1.5?)(b)40 residues→ 36 (4 for hairpin turn) →18 (two-stranded) → 63? (the rise per residue 3.5?in βsheet) motif基序? mom基基t

2. contrasting isomer截然不同的异构体 dioxane二噁烷 in Leu methyl甲基 is attached to γ-C atom, while in Ile it to β-C atom(比较靠近主链α-碳原子,造成立体位阻,阻断α-螺旋的形成)

3. Ala ＜ Val; Ile ＞ Gly …Ala……Ile….. with activity (wild type) …Val……Ile…… lose activity (mutant type) …Val……Gly… regain activity (double-mutant

type)

4. shuffle重新洗牌, disulfide-sulfhydryl exchange二硫键-巯基互换; PDI蛋白二硫键异构酶, scrambled ribonuclease杂乱的核糖核酸酶

杂乱的核糖核酸酶在PDI作用下由无序变成有序,而胰岛素则由有序变成无序,说明胰岛素结构并非热力学最稳定的形式;因为胰岛素是由(比它多33个残基的)胰岛素原形成的,后者才是热力学最稳定的形式.

5.stretching a target使目标(蛋白底物)伸展; protease蛋白水解酶

6. Gly has the smallest side chain of AA: tight turns and approaching one another closely

7.guanidinium group胍基 of Arg (positive): Glu, Asp, and the terminal carbonyl group (negative)

8.keratin角蛋白 烫发: 加入巯基化合物(作为还原剂)和适当的温度使原来(发型中)的二硫键打断,卷曲头发(至所需型态)并加入氧化剂,使之形成新的二硫键并稳定.

Chapter 3

1.(a)phenyl isothiocyanate (PITC) 异硫氰酸苯酯 (b)Dansyl chloride丹黄酰氯(or dabsyl chloride) (c)Urea尿素; β-mercaptoethanol β-巯基乙醇

(d)chymotrypsin糜蛋白酶 (N)……R-‖-X……(C) R: Phe Trp, Tyr (e)CNBr (N)……Met-‖-X……(C)

(f)Trypsin (N)……R-‖-X……(C) R: Arg or Lys

2. K=[H+][A－]/[HA] → pH=pK +log [A－]/[HA]

3.anhydrous hydrazine无水肼: 处理多肽(蛋白质)发生裂解,羧基末端的氨基酸释放成游离氨基酸,可被鉴定.所有其他氨基酸残基变成酰肼衍生物.

4. ethyleneimine乙烯亚胺 + Cys → S-aminoethyl氨乙基 derivatives (S-氨乙烯半胱氨酸) →与Lys类似 Cys*-‖-X

5. incident入射, transmitted透射, εextinction coefficient (molar absorption coefficient)消光系数; I = I0 10－εlc A (log I0/I) =εlc

1mg/ml →5.62 x 10－5 M (MW= 17.8 kd) A = 15000 x 5.62 x 10－5 x 1= 0.84 = log10(I0/I) I0/I=6.96 即14.4%的入射光被透射

6. tropomyosin原肌球蛋白rod shaped

7.s ∝ m/f f = 6πηr m ∝ r3 → s ∝ m2/3

8. y = kx + b log (MW) = k (RM) + b y— log (MW) MW:molecular weight X—RM: relative mobility log 92000 = 0.41 k + b

log 30000 = 0.80 k + b k= －1.26 b= 5.465

So, the apparent mass of a protein having a mobility of 0.62 is 50 kd

Chapter 4

1.

5’ GATCAA 3’

3’ CTAGTT 5’→5’TTGATC3’(书写自左向右5’→3’) 3. 17μm－15μm = 2μm = 20000A÷3.4A = 5800 base pairs

4．A(15N) B(14N)

Conservative replication: AA→ AA+BB (F1)→ AA+BB+ BB+ BB(F2) Semiconservative replication: AA→ AB+ AB (F1) →AB+ AB +BB+ BB (F2)

6. competence感受态 Bacillus subtilis枯草芽胞杆菌

possible reason: 1.not able to take up DNA 2.having deoxiribonuclease脱氧核糖核酸酶 3.not able to integrate fragments of DNA into their genome

7. propitious有利的; T2 is used by Hershey and Chase (P78) to separate itself into genetic (DNA) and nongenetic (protein) parts. M13 is not. (它的蛋白外壳将嵌入宿主的内膜,离心后将随细胞沉淀)

8. （a）tritiated thymine (or thymidine)氚标记的胸腺嘧啶（胸苷）T*→ dTTP* →DNA* (b) dNs-P*~P~P 9.

5’_______________3’-OH 3’-OH_______________5’

10. reverse transcriptase逆转录酶 polyriboadenylate聚腺苷酸 primer引物 deoxythymudylate oligonucleotide寡聚脱氧胸苷酸

template: poly(rA) →primer oligo dT ＋ synthetic material dTTP

3’ …AAAAAAAAAAA… 5’ TTT(OH)…

11.RNA→DNA-RNA hybrid → DNA transcript → double-helical viral DNA (＋) (－ ＋) (－) (±)

(both by reverse transcriptase) ribonuclease核糖核酸酶； polymerase聚合酶; 逆转录酶兼具聚合酶和核糖核酸酶的功能 12．Turnip 芜菁 Virus → treated with phenol苯酚 (to remove protein) →NA (divide into two samples)

1. treated with ribonuclease核糖核酸酶

2. treated with deoxyribonuclease脱氧核糖核酸酶

13．G-C → G-U (by deamination脱氨) →G-C ＋A- U (after one round of replication)

→G-C ＋ G-C ＋ A- U ＋ A- T (after two round of replication)

14. hydrogen cyanide氰化氢(HCN) pentamer五聚体 adenine腺嘌呤(H5C5N5)

15. (a) AA AC AG AT 24

CA CC CG CT

GA GC GG GT TA TC TG TT

CHAPTER 5

1. (a) dATP, dCTP, dGTP, dTTP (for DNA); ATP, CTP, GTP, UTP (for RNA)

2. (a) 3’–ATTGCCATGCTA-5’

5’-UAACGGUACGAU-3’

(b) 5’-UUGCCUAGUGAUUGGAUG-3’ N-Leu—Pro—Ser—Asp—Trp—Met-C

? 5’-UUACUUACUUACUUACUUACUUAC…-3’ Poly(UUAC) N-Leu—Leu—Thr—Tyr--Leu—Leu—Thr—Tyr-C

Poly(Leu-Leu-Thr-Tyr)

5’-UUACUUACUUACUUACUUACUUAC…-3’

N- Tyr- Leu- Leu- Thr….. Poly(Tyr-Leu-Leu-Thr) 5’-UUACUUACUUACUUACUUA -3’

N- Thr - Tyr- Leu – Leu…. Poly(Thr-Tyr-Leu-Leu)

4. ccordycepin蛹虫草菌素 3’-deoxyadenosine脱氧腺苷 It terminates RNA synthesis because it lacks a 3’-OH group.

5. poly(G)聚鸟苷酸forms a triple-stranded structure三股螺旋结构, therefore it can’t serve as a template for protein synthesis. Poly(A), poly(C) and poly(U) can do as single-stranded RNA.

6. 5’…TACTACTAC…3’

3’… ATGATGATG ATGATGATG…5’ ↓DNA聚合酶，连接酶