生物大分子課件：bio-coures-5

1、General introduction about silk Silk is a kind of natural product. This material is superior to almost synthetic fibers with regard to the combination of energy to break and tensile strength. Understanding the concepts of this remarkable feature and translating it to synthetic materials can result i

2、n improved engineering polymers. 桑蠶絲素蛋白的分子量約為桑蠶絲素蛋白的分子量約為 2.5 105 3.5 105Amino acid Native B. mori silk fibroin Regenerated B. mori silk fibroin ASP/ASN 2.4 1.46 THR 1.6 0.8 SER 12.3 10.8 GLU/GLN 1.2 0.9 PRO 0.7 0.5 GLY 43.5 46.2 ALA 28.0 29.7 CYC 0.1 Not determined VAL 2.3 2.1 MET 0.1 0.1 ILE 0.6 0

3、.5 LEU 0.5 0.4 TYR 5.0 4.9 PHE 0.7 0.6 HIS 0.2 0.2 LYS 0.5 0.3 ARG 0.6 0.4 Amino acid composition (mol%) of native and regenerated by B.m. silk fibroin氨基酸殘基的主要序列為：氨基酸殘基的主要序列為：GAGAGS or GAGAGAGS存在至少兩個(gè)非二硫鍵連存在至少兩個(gè)非二硫鍵連接的亞單元接的亞單元SpidersThere are more than 35,000 kinds of spider living in this world. The

4、ir history can be trace back to 400 million years ago.Other spiders and webs Bolars spiderNetcasting Spider蜘蛛能分泌多種具有不同功能的絲蛋白蜘蛛能分泌多種具有不同功能的絲蛋白Spider silks從其主腺體從其主腺體(Major Ampullate) 中中吐出的絲是目前研究的主要對(duì)象吐出的絲是目前研究的主要對(duì)象Spider s spigots and silksAmino acid compositions of various spidroin蠶絲素蛋白纖維的蠶絲素蛋白纖維的不規(guī)則性

5、不規(guī)則性Hierarchical structure of Bombyx mori silk研究動(dòng)物絲和絲蛋白的意義 絲所獨(dú)具的優(yōu)異力學(xué)性能 非常溫和且友好的成絲過程（蛋白質(zhì)的構(gòu)象變化 ） 絲及其絲蛋白的環(huán)境可降解性 絲及其絲蛋白的生物相容性 絲及其絲蛋白的化學(xué)和物理可修飾性 目前即使質(zhì)量最好的人目前即使質(zhì)量最好的人造高分子材料，在彈性、造高分子材料，在彈性、斷裂吸收能、纖維長(zhǎng)度、斷裂吸收能、纖維長(zhǎng)度、重量比等綜合力學(xué)性能上重量比等綜合力學(xué)性能上依然還無(wú)法超越自然界中依然還無(wú)法超越自然界中的動(dòng)物絲。的動(dòng)物絲。通過對(duì)絲及其相關(guān)蛋白質(zhì)的分析，建立天然生物大分子和合成高分子之間的聯(lián)系，最終找到人工生

6、產(chǎn)具有類似特性產(chǎn)品的方法成絲過程的成絲過程的神奇之處神奇之處合成纖維：110 m/s液晶的形成液晶的形成蛋白質(zhì)構(gòu)象的轉(zhuǎn)變蛋白質(zhì)構(gòu)象的轉(zhuǎn)變Mystic spinning process of animal?動(dòng)物絲：12 cm/s水不溶水不溶的纖維的纖維園二色譜園二色譜小角小角X射線衍射射線衍射偏光顯微鏡等偏光顯微鏡等拉伸儀拉伸儀拉曼光譜儀拉曼光譜儀廣角廣角X射線衍射射線衍射流變儀等流變儀等蛋白質(zhì)的蛋白質(zhì)的自組裝自組裝水溶性水溶性的凝膠的凝膠動(dòng)物紡絲的動(dòng)物紡絲的速率遠(yuǎn)低于速率遠(yuǎn)低于合成纖維合成纖維各種影響因素?各種影響因素?Silkgland of Bombyx mori. AB: Ant. di

7、vi., 35mm, 0.050.3mm ; BC: Middle divi., 65mm, 1.22.5mm ; CD: Post. divi., 220, 0.40.8mm Fiberization of B. mori silk fibroin水分揮發(fā)水分揮發(fā)拉伸應(yīng)力拉伸應(yīng)力高剪切應(yīng)力高剪切應(yīng)力蛋白質(zhì)濃度增大蛋白質(zhì)濃度增大有序化開始有序化開始分子鏈排列分子鏈排列分子鏈進(jìn)一步有序排列分子鏈進(jìn)一步有序排列12絲素水溶液，無(wú)規(guī)線團(tuán)絲素水溶液，無(wú)規(guī)線團(tuán)20水凝膠，水凝膠，復(fù)合螺旋復(fù)合螺旋23水凝膠，水凝膠，無(wú)規(guī)的螺旋無(wú)規(guī)的螺旋+-螺旋螺旋25水凝膠，水凝膠， -螺旋螺旋+拉開的螺旋，液晶形成拉開

8、的螺旋，液晶形成30水凝膠，水凝膠， -折疊，向列型液晶折疊，向列型液晶固體絲，高取向的固體絲，高取向的 -折疊結(jié)構(gòu)折疊結(jié)構(gòu)Dissected MA gland & associated structure (Nephila Edulis)a, A-zone; b, B-zone; f, funel; 1,2,3, first, second and third limbs of duct; m, duct levator muscle; v, valve; vm, valve tensor muscle; t, terminal tubule; s, spigot. Scale ba

9、r 1mmThe formation of spider silk in duct(B) As A, but showing a highly shortened draw down taper and coiling of a thread in the distal part of the third limb of the duct before the valve. The shortening of the draw down taper is likely to result from stress release on rupture. Scale bar 50 m.(A) In

10、terference contrast micrograph of whole mount showing a helical twisting of the thread within the lumen of third limb of the duct at the start of the draw down taper in an individual with an unruptured thread. This could result from a spontaneous coiling of the thread or from the proposed twisting a

11、ction of the valve. Scale bar 50 m.States of liquid fibroin in B. mori silk glandMechanical properties of silksCocoon silk斷裂能 (X10 KJ/Kg)0246810121416蜘蛛絲蠶繭絲凱夫拉纖維纖維素纖維肌腱骨高延展性鋼Mechanics of single filament of spider silkSpider silk has a large recoverability after it is stretched, not only under normal

12、 condition, but in the selected solventsStress-strain curves of Araneus d. dragline during (wet state) and after(re-dried state) contraction in the liquids. Shortage was defined as negative strainOrientation of -sheet in silksSingle fiber was aligned either parallel (solid line) or perpendicular (da

13、shed line) to the direction of polarization of laser beamRaman spectra of (A) major ampullate silk of Nephila edulis, and (B) degummed silk of Bombyx moriRaman spectra of (A) major ampullate silk of Nephila edulis, and (B) degummed silk of Bombyx moriAFM images of spider silk取向的微纖維結(jié)構(gòu)取向的微纖維結(jié)構(gòu)絲纖維長(zhǎng)軸方向絲

14、纖維長(zhǎng)軸方向TEM pictures of spider MA silkScale bar=0.2mThe micrographs of contracted spider silkCD experiment of silk fibroinThe regenerated silk fibroin solution was prepared by dissolving the degummed silk fiber into a 9.3 mol/L LiBr solution and then dialyzed against distilled water. Resultant regener

15、ated silk fibroin concentration is about 1% (w/w), and then was diluted to 0.1% for CD experiment.The regenerated silk fibroin was demonstrated to have the same secondary structure (random coil) as that in the gland of silkwormJasco J-715 spectropolarimeter equipped with a slab (NESLAB RTE-111) Path

16、 length of cell: 1mmTime range: 8 hrs190200210220230240250-12-10-8-6-4-202 Wavelength (nm)observed ellipticity obsTime resolved CD spectra of SF aqueous solution with and without -sheet “seeded”190200210220230240250-10-8-6-4-202468 observed ellipticity obsWavelength (nm) -sheet “seed” free1902002102

17、20230240250-10-8-6-4-202468observed ellipticity obsWavelenth (nm)190200210220230240250-10-8-6-4-202468 Wavelenth (nm)observed ellipticity obs5% -sheet “seed” added20% -sheet “seed” addedTime range: 0233 hoursConcentration of fibroin: 0.1% (wt/wt)Time and “seeded” dependence of conformation transitio

18、n of fibroin190200210220230240250-8-6-4-20246Wave length (nm) 5 54 41. 0 hours1. 0 hours2. 6 hours2. 6 hours3. 18 hours3. 18 hours4. 74 hours4. 74 hours5. 233 hours5. 233 hoursA3 32 21 1 (10-3deg cm2/dmol)190200210220230240250-4-202461. 0 hours1. 0 hours2. 6 hours2. 6 hours3. 18 hours3. 18 hours4. 7

19、4 hours4. 74 hours5. 233 hours5. 233 hours5544B332211 (10-3deg cm2/dmol)wavelength (nm)Original 0.1% silk fibroin solution20% -sheet seeded solution050100150200250-0.20.00.20.40.60.81.01.2ANormalized ellipticity 217Time course (hrs)The lag time in unseeded solutionSeed-free20% seed involved02468100.

20、800.850.900.951.001.051.10Normalized ellipticity 217time course (hrs)02550751000.00.20.40.60.81.0BNormalized ellipticity 217Time course (hrs)5% seed involved0.1 mg/ml silk fibroin solutionreveals a slower -sheet formation speed in a lower silk fibroin concentration with 20% -sheet seeded ( 0.01; 0.1

21、 mg/mL silk fibroin solution) Acoil A First-order dynamic process of aggregator growthLinear plots of ln(1-217) versus time course with different seed concentrations coilcoilAkdtAd05010015020025001234slope 0.0181 (0.0009) R 0.9748-ln(1- 217)Seed-free05010015020025001234slope 0.0179 (0.0010) R 0.9566

22、-ln(1- 217)5% seed05010015020025001234slope 0.0151 (0.0010) R 0.8941-ln(1- 217)time course (hours)20% seedln(1-nor217) = ktScheme of nucleation-dependent aggregation for silk fibroinWhy is the spin rate of nature silk so slow by comparison with synthetic fiber, but its molecular chain still has such

23、 high orientation?shearing forcerandom coil unit -sheet unitnucleinucleation induced by silk pressaggregation growthTime-resolved FTIR spectra of silk fibroin membrane4000 3500 3000 2500 2000 1500 10000.00.51.01.52.0AbsorbanceFrequency (cm-1)Amide IAmide IIAmide A, BFREQUENCY (cm-1) ASSIGNMENT (Susi

24、, 1969)3300Amide A: NH stretch3100Amide B: NH stretch1690-1600Amide I: CO stretch1575-1480Amide II: NH stretch, CN stretch1301-1229Amide III: CN stretch, NH bendAmide I Secondary Structure Assignments:1620 - 1640 -sheet1644random coil (D2O)1648 - 1657-helix1665310 helix1670 - 1695 anti-parallel -she

25、et, -turnSCAN PARAMETERS: regenerated silk fibroin membrane, 5m thick Nicolet Magna 860 FTIR spectrometer BaF2 liquid cell, path length 15 m 70% ethanol/30% D2O solution 64 scans per spectrum, 4 cm-1 resolution interval between two successive spectra: 5.85 sec MCT detectorAmide I band of regenerated

26、 Bombyx mori silk fibroin(a) membrane without any treatment; (b) membrane immersed in 70% ethanol for 24h and then dried; (c) the first spectrum (at 0.1 min) in the dynamic measurement (curve Ablack: normal FTIR spectrum; curve Bblue: second derivative spectrum)17201700168016601640162016000.00.40.81

27、.21.6AbsorbanceWavenumbers (cm-1)0.00BA(b)Arbitrary Units 17201700168016601640162016000.00.51.01.52.0AbsorbanceWavenumbers (cm-1)0.00BA(a)Arbitrary Units 17201700168016601640162016000.00.40.81.21.62.0AbsorbanceWavenumbers (cm-1)-0.010.000.01BA(c)Arbitrary Units Time-resolved FTIR spectraFTIR spectra

28、 of regenerated silk membrane during the conformation transition process from beginning to 60minDifference spectra obtained from left spectraConformation transition kinetics of B. mori fibroin membrane0102030405060-0.25-0.20-0.15-0.10-0.050.00(b)silk fibroin in 70% ethanol-helix at 1668 cm-1Data: Da

29、ta2_BModel: ExpDecay2Chi2 = 0.00001y0-0.231720.00086x000A10.148990.00592t10.518480.04195A20.109850.00561t25.261930.36352AbsorbanceTime (min)01020304050600.00.10.20.30.4(a)silk fibroin in 70% ethanol-sheet at 1618 cm-1Data: Data1_BModel: ExpDecay2Chi2 = 0.00003y00.327440.0011x000A1-0.27310.00919t10.5

30、29350.03448A2-0.103140.00942t24.509250.49955AbsorbanceTime (min)Fits with biphasic exponential decay functionsPossible three phases in the conformation transition of SF Notes: The time constants, , and the amplitudes were obtained by the absorbance difference spectral amplitudes with exponential dec

31、ay functions. The relative amplitudes 1 and 2 were calculated by 1=A1/(A1 + A2 ) and 2=A2/(A1 + A2 ), respectively (where A1 and A2 are the amplitudes of the first and the second phase.Conformation transition kinetics of B. mori silk fibroin membranes probe byabsorbance changes of -sheet band at 161

32、8 cm-1 and random coil band at 1668 cm-1IR marker (min)1(%) (min)2(%)-sheet band at 1618 cm-10.560.046745.200.47332Random coil at 1668 cm-10.510.056345.800.61373Burst phase: 50% of -sheet structure achieved Second process: 33% of -sheet formedThird process: “perfects” -sheet structure FTIR spectra o

33、f Nephila spidroin film during the conformation transition process Original FT-IR spectraThe conformation transition process induced by K+ from beginning to 240 min.Difference FT-IR spectraConformation transition kinetics of spidroin film probed by absorbance changes of -sheet band1620cm-1 1691cm-1

34、KCl (mol/L) 1 (min) 2 (min) 1 (%) 1 (min) 2 (min) 1 (%) 1.0 7.42.4 53.39.5 517 7.82.1 54.96.2 437 0.5 4.52.5 49.88.2 439 4.02.3 53.92.2 337 0.3 3.70.2 48.67.0 315 3.00.2 57.75.9 216 (min) (min) 0.1 61.47.3 69.44.8 0.05 66.37.0 70.78.5 0.01 66.56.1 72.55.9 050100150200250-1.0-0.8-0.6-0.4-0.20.0(a) 1.

35、0M 0.5M 0.3M 0.1MAbsorbanceTime (min)050100150200250-1.0-0.8-0.6-0.4-0.20.0(b) 1.0M 0.5M 0.3M 0.1MAbsorbanceTime (min)蜘蛛絲優(yōu)于蠶絲？！Materials Key repetitive sequences Fibroin Gly-Ala-Gly-Ala-Gly-Ser Spidroin (Ala)n, Gly-Gly-Gln, Gly-Ala-Gly, Gly-Gly-X 生物化學(xué)角度：蠶絲蛋白和蜘蛛絲蛋白的氨基酸組成和一級(jí)結(jié)構(gòu)之間的差異很大原因？蜘蛛絲在一般情況具有高模、高強(qiáng)

36、、高彈性及很高的斷裂吸收能等優(yōu)異的綜蜘蛛絲在一般情況具有高模、高強(qiáng)、高彈性及很高的斷裂吸收能等優(yōu)異的綜合力學(xué)性能吸引科學(xué)家們?cè)噲D大量地得到這一材料。合力學(xué)性能吸引科學(xué)家們?cè)噲D大量地得到這一材料。Synthesis of spidroin？對(duì)于絲這一類非生理活性的蛋白質(zhì)，一級(jí)結(jié)構(gòu)是否能決定其最終性能對(duì)于絲這一類非生理活性的蛋白質(zhì)，一級(jí)結(jié)構(gòu)是否能決定其最終性能轉(zhuǎn)基因山羊奶轉(zhuǎn)基因山羊奶大腸桿菌或酵母大腸桿菌或酵母Nexia公司公司DuPont公司公司Biosilk類蜘蛛類蜘蛛絲蛋白絲蛋白(SGRGGLGGQGAGAAAAAAA)n及及(AAAGGAGQGGYGGLGSQGT)n蜘蛛絲蛋白的氨基酸基本

37、組成序列Stress-strain curves of recombinant silkNexia Biotechnologies Produced soluble recombinant (rc) dragline silk proteins with molecular masses of 60 to 140 kilodaltons by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. Spun monofilaments from a

38、 concentrated aqueous solution of soluble rcspider silk protein under modest shear and coagulation conditions. The spun fibers exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. A. Lazaris etal, SCIENCE, 295, 2002 472-476Formation of regenera

39、ted silksGuanidine-HClSelf-assembling of spidroinor dialysisNative SilkSolution8M12% aqueous solution Gel filtration / Protein aggregated on the surface of solution, the fiber-like regenerated silk could be drawn with the techniquesNuclear dependent aggregationRegenerated silk is also water insolubl

40、e.Morphology of regenerated spider silkOriented fibrils or wrinklesCompared to the smooth surface of native silk drawn from the spider, the regenerated spider silk had a much more rougher surface. But notwithstanding the wrinkles along the long axis of the fiber, the surface of regenerated silk is s

41、till quite even and with an average diameter of about 9m only slightly thicker than that of native spider silk. Amino acid composition (mol%) of native spider silk proteins and regenerated silkThe amino acid compositions of our native and regenerated N. edulis silks were nearly identical. Guanidine

42、hydrochloride only disrupts the non-covalent interaction in the proteins. Assumed that the primary structure of silk proteins experienced no serious changes during the dissolution of the native silk and its reformation. Thus the observed differences between both silks in mechanical properties would

43、in most probability be caused by their differences in secondary and/or condensed structure of the silk proteins.Amino acid Native N. edulis MA silk (reeled) Regenerated N. edulis silk N.clavipes spidroin (from MA gland)* N.clavipes MA silk (reeled)* ASP/ASN 1.5 0.7 1.9 1.06 THR 0.4 0.3 1.0 0.34 SER

44、1.7 1.8 3.0 2.24 GLU/GLN 12.8 13.2 10.1 11.02 PRO 9.4 6.7 1.7 2.04 GLY 38.2 39.9 40.3 49.96 ALA 24.0 25.7 28.4 22.71 CYC Not determined Not determined Not determined 0.06 VAL 0.7 0.6 1.5 0.89 MET 0.3 0.1 0.3 0.04 ILE 0.4 0.2 0.6 0.07 LEU 2.4 2.7 4.5 4.26 TYR 5.2 4.7 3.1 2.99 PHE 0.3 0.2 0.5 0.26 HIS

45、 Trace 0.9 0.02 0.21 LYS 0.3 0.2 0.8 0.10 ARG 2.3 2.2 2.0 1.76 * Tillinghast, E. K. and Christenson, T. (1984) J. Arachnol., 12, 69-74 * Work, R. W. and Young, C. T. (1987), J. Arachnol., 15, 65-80 Stress-strain curves of regenerated silk0.000.050.100.150.200.250.300.350.400.000.020.040.060.080.100.

46、120.140.160.18streched in waterstretched in air Stress (GPa)Straininitial modulus : 6.0 GPa ;breaking strength: 0.11 to 0.14 Gpa; breaking elongations varied between 10% and 30%. neither the initial modulus nor the strength of our regenerated silk could compete with those of native dragline silk the

47、 relatively poor mechanical properties of our regenerated silk was due to its formation by a self-assembling process of molecular chain aggregation instead of the complex liquid crystal spinning of native silk Loading-unloading cycles of spider silks0.000.020.040.060.080.100.120.140.160.180.00.10.20

48、.30.40.50.60.70.8 regenerated silk native silk shrunk silkStress (GPa)Straina large degree of permanent setting after the first cycle showed in regenerated silksuggested that the molecular chains in the regenerated silk were rather disorientated Solid line: parallelDashed line: perpendicularRaman sp

49、ectra of native and regenerated spider silkNative silkRegenerated silk:nearly isotropic -sheet and slightly difference between productsHierarchical structure of silks(Ala)n, n=47帶絲膠的桑蠶絲蜘蛛絲從高分子凝聚態(tài)的角度看，蠶絲和蜘蛛絲的微觀結(jié)構(gòu)非常相似從高分子化學(xué)的角度看，蠶絲蛋白和蜘蛛蛋白的主鏈非常一致What can we do from point of view in polymer science動(dòng)物絲素蛋白

50、為結(jié)構(gòu)性纖維蛋白，其分子量約在300,000400,000之間，且沒有明顯的生理活性適合從高分子物理和化學(xué)的角度適合從高分子物理和化學(xué)的角度來(lái)進(jìn)行理解和研究？！來(lái)進(jìn)行理解和研究？！鏈結(jié)構(gòu)，制備過程，聚集態(tài)結(jié)構(gòu)，性能Dissected MA gland & associated structure (Nephila E.)Dissected silk gland of Bombxy moriSingle filament of spider silk in various conditionsStress-strain curves of Araneus d. dragline duri

51、ng (wet state) and after(re-dried state) contraction in the liquids. Shortage was defined as negative strainThe difference of native and shrunk silk on mechanics is because of the secondary structure and its orientation of silk protein changed具有不同性能的蜘蛛絲，有著不同的二級(jí)和聚集態(tài)結(jié)構(gòu)具有不同性能的蜘蛛絲，有著不同的二級(jí)和聚集態(tài)結(jié)構(gòu)Mechanics

52、 of spider silks reeled in various conditionsThe silks obtained from a starved spider in different stages We have done 動(dòng)物絲及絲蛋白的性能與其二級(jí)結(jié)構(gòu)和聚集態(tài)結(jié)構(gòu)密切相關(guān)； 蜘蛛絲的力學(xué)性能不僅與蜘蛛本身的狀態(tài)有關(guān)，而且依賴于其制絲時(shí)的條件（溫度、抽絲速度及環(huán)境等）； 經(jīng)過各種處理（如在水中超收縮等）后，蜘蛛絲的力學(xué)性能發(fā)生很大的改變，同時(shí)伴隨著絲蛋白的二級(jí)以上結(jié)構(gòu)的變化； 動(dòng)物絲有特別的形態(tài)，如多相結(jié)構(gòu)、皮芯結(jié)構(gòu)等，由此可以解釋為何動(dòng)物絲具有出色的韌性等特性； 我們希望通過

53、這些研究，來(lái)突現(xiàn)絲蛋白及絲纖維（結(jié)構(gòu)性蛋白質(zhì)）的制備過程、二級(jí)和聚集態(tài)結(jié)構(gòu)對(duì)絲性能的主要貢獻(xiàn)說服力如何？說服力如何？蠶絲和蜘蛛絲： 成絲機(jī)理（蛋白質(zhì)的構(gòu)象轉(zhuǎn)變）一致 二級(jí)結(jié)構(gòu)和分子鏈聚集態(tài)結(jié)構(gòu)非常相近？其力學(xué)性能的差異如此之大爭(zhēng)論焦點(diǎn)：爭(zhēng)論焦點(diǎn)：用于力學(xué)性能測(cè)量的蠶絲和蜘蛛用于力學(xué)性能測(cè)量的蠶絲和蜘蛛絲，在其制樣過程中有何不同？絲，在其制樣過程中有何不同？Single filament of silks for measurement 蠶繭在蠶繭在(堿性堿性)熱水中脫膠熱水中脫膠繅絲過程繅絲過程Whats the real strength of silkworm silk?Mechanics

54、 of silkworm silk reeled under different speedsWhat does the role of sericin play in the mechanics of worm silk?Degummed silkUndegummed silkForce-strain curves of silkworm silk with and without sericin為何蠶絲的力學(xué)性能不如蜘蛛絲？為何蠶絲的力學(xué)性能不如蜘蛛絲？為何為何繭絲繭絲的力學(xué)性能不如蜘蛛絲的力學(xué)性能不如蜘蛛絲或直接勻速拉出的蠶絲？或直接勻速拉出的蠶絲？The formation of si

55、lkworm cocoonHow does the spinning behavior of silkworm works on silk mechanics0.00.10.20.30.40102030405060 Force (mN)Strain0.000.050.100.150.200.250.300.350102030405060 Force (mN)StrainStatistics of “forced” spinning silkworm silk Amount of test Strain Breaking Elongation (%) Module (GPa) Breaking

56、Strength (GPa) Breaking Energy (104J/kg) 9 0.0310.094 62 14.10.5 0.480.13 1.40.8 29 0.1010.199 153 14.20.2 0.600.12 4.81.4 30 0.2060.295 253 14.20.2 0.650.11 9.41.5 30 0.3100.445 354 14.20.2 0.730.11 13.72.3 7 0.2720.350 323 10.80.4 1.40.1 15.72.5 12 filaments from 6 silkworms. Total measurement : 9

57、8Typical mechanical properties of spider (Nephila Edulis) silkThe defects of spinned silkworm silkConclusions對(duì)結(jié)構(gòu)性蛋白質(zhì)而言，其二級(jí)結(jié)構(gòu)和聚集態(tài)結(jié)構(gòu)等對(duì)力學(xué)性能的貢獻(xiàn)非常大若對(duì)蠶進(jìn)行特殊處理，如改變吐絲習(xí)性、除去絲膠蛋白、甚至找到合適的方法直接取絲，有可能得到綜合力學(xué)性能可與蜘蛛絲媲美的蠶絲若希望人工制得性能優(yōu)異的類天然蛋白纖維，對(duì)動(dòng)物的吐絲過程和成絲機(jī)理的研究是必不可缺的，其中最主要的應(yīng)是蛋白質(zhì)（分子鏈）自組裝成特定結(jié)構(gòu)的行為、能力和各種影響因素以“基因工程”得到的蜘蛛絲蛋白作為研

58、究材料固然可行，但用現(xiàn)有的蠶絲蛋白研究超級(jí)纖維形成和制備則是“捷徑”。而希望通過“轉(zhuǎn)基因”技術(shù)而使蠶吐“蜘蛛絲”則可能在提高絲纖維的力學(xué)性能上的價(jià)值不大對(duì)合成纖維而言，通過仿生的手段改變其紡絲的過程從而改變其聚集態(tài)結(jié)構(gòu)以達(dá)到改善性能的余地很大。 蜘蛛絲在水中的超收縮通常，蜘蛛主腺體絲能夠在（冷）水中延纖維長(zhǎng)軸方向縱向收縮，收縮程度主要依賴于蜘蛛的種類爭(zhēng)論焦點(diǎn)之二爭(zhēng)論焦點(diǎn)之二：蜘蛛絲超收縮的本質(zhì)To be evolved on purpose從蜘蛛絲蛋白的一級(jí)結(jié)構(gòu)上尋找原因蜘蛛主腺體絲蛋白的基本序列結(jié)構(gòu)蜘蛛次腺體絲蛋白的基本序列結(jié)構(gòu)桑蠶絲蛋白的基本序列結(jié)構(gòu)彈性蛋白具有同樣的基序彈性蛋白具有同樣的

59、基序目的：網(wǎng)的張力？！蜘蛛絲在水中的超收縮每天13個(gè)月織網(wǎng)頻率一生1次蜘蛛絲超收縮的本質(zhì)To be constrained in evolution從蜘蛛絲的二級(jí)結(jié)構(gòu)以及聚集態(tài)結(jié)構(gòu)上尋找原因051015200.100.150.200.250.300.350.40Shrinkage (%)Spnning Speed (cm/s)不同的成絲條件，不同的超收縮率 紡絲速度 水分揮發(fā) 紡絲溫度 紡絲環(huán)境 不同個(gè)體 我們發(fā)現(xiàn)，原絲的斷裂伸長(zhǎng)越大，其在水中的收縮率越?。〕山z條件力學(xué)性能超收縮率蜘蛛絲力學(xué)性能與其超收縮率的相關(guān)性直徑直徑原絲力學(xué)性能原絲力學(xué)性能收縮率及收縮率及收縮后力學(xué)性能收縮后力學(xué)性能收縮

60、率和各項(xiàng)力學(xué)性能之間的關(guān)系 * Correlations can also be established between Csh and stress at other strains (Liu et al unpublished data)* SE is the standard error of the fitting curve.* R2 is the square of correlation coefficient.* N is the number of points involved in curve fitting. 0.000.050.100.150.200.250.300.350.400.