• 한국잠사곤충학회지
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• 제40권2호
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• pp.131-135
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• 1998

Changes of silk fibroin molecular weight was studied by enzymatic proteolysis and reverse reaction of enzymatic proteolysis (plastein reaction) using chromatography, X-ray diffraction and thermal analysis methods. When the treatment of enzymatic proteolysis with $\alpha$-chymotripsin to silk fibroin solution, a precipitate of Fcp fractions was formed. And, this was dissolved in LiBr aqueous solution, the precipitate of PIFcp fractions was obtained again. Fcp and PIFcp fractions showed silk IIand silk Itype structure, respectively. Fcp fractions was about 6,900 in molecular weight, PIFcp fractions obtained by plastein reaction on the precipitate of Fcp fractions increased molecular weight to abort 15,000. The molecular weight of Fcp fractions was increased by plastein reaction, but Fcp fractions almost transited to silk I type crystal. The structure of silk I type of PIFcp fractions was steady identified by X-ray diffraction and thermal analysis. As molecular weight of Fcp fractions was gradually low, PIFcp fractions was become to macromolecule little by little.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.197-202
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• 1997

To hydrolyze silk fibroin was treated with NaOH solution on various concentrations and times. And it was examined that the addition effects of NaHSO3 solution on the solubility and colouring of silk fibroin. As obtained results are as follows; The more increasement of concentration and time of NaOH treatment, the more increasement of solubility but solubility was slight above 3% concentration of NaOH. Fibroin yield was decreased above 3% concentration. This was due to formation of peptide or amino acids below molecular weight 3,000. Most of molecular weight distribution came out to be under 3,000 in 2% concentration and 4hrs of NaOH treatment. The more increasement of adding concentration and 4hrs of NaOH treatment. The more increasement of adding concentration of NaHSO3, the more reduction of solubility but white index of powder increased. In the results of FT-IR spectras of silk fibroin powder obtained by various concentrations of NaHSO3 treatment, the absorbent peak at 3,400 cm-1 which was considered as -CH=N- (azomethine) was disappeared by the more addition of NaHSO3. It showed that absorbent peak of $\beta$-fibroin moved into low temperature region and transferred to $\alpha$- and random coil structure through the DSC experiment. In the results of amino acid analysis, alkali hydrolysis reduced the oxy amino contents acid like serine and tyrosine, but increased the glycine content by the more addition of NaHSO3.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권1호
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• pp.29-33
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• 2004

Low molecular weight silk fibroin (LMSF), which was prepared by hydrolysis of silk fibroin using high-temperature and high-pressure method, was found to inhibit the oxidation of L-3,4,-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase (EC 1.14.18.1). LMSF contained mostly free amino acids such as L-glycine, L-alanine, and L-serine and oligopeptides, mainly glycine-alanine dimer. As a result of analyzing the inhibition kinetics from Lineweaver-Burk plots, L-glycine and glycine-alanine dimer showed noncompetitive behavior while uncompetitive behavior was observed in L-alanine, and L-serine. When weight percent concentration of ${ID_50}$ was compared, L-glycine was most effective on the inhibition and LMSF was also good enough for the inhibition effect of tyrosinase activity. LMSF showed a mixed-type inhibition and the inhibitory mechanism of LMSF might be caused by free amino acids and oligopeptides. As a result of spectroscopic observation with time, initial rate of increase of DOPAchrome decreased remarkably and the time to reach maximum absorbance increased as an increase of the concentration of L-glycine, meaning that L-glycine made itself mainly responsible for the formation of chelate with ${Cu^2+}$ in tyrosinase. However, in case of L-alanine, L-serine, and especially glycine-alanine dimmer, the production of DOPAchrome after an arrival at maximum absorbance decreased, indicating the production of adducts through the reaction with DOPAquinone.

• BMB Reports
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• 제43권1호
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• pp.52-56
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• 2010

Silk fibroin, produced by the silkworm Bombyx mori, has been widely studied as a scaffold in tissue engineering. Although it has been shown to be slowly biodegradable, cellular responses to degraded silk fibroin fragments are largely unknown. In this study, silk fibroin was added to MG-63 cell cultures, and changes in gene expression in the MG-63 cells were screened by DNA microarray analysis. Genes showing a significant (2-fold) change were selected and their expression changes confirmed by quantitative RT-PCR and western blotting. DNA microarray results showed that alkaline phosphatase (ALP), collagen type-I alpha-1, fibronectin, and transforming growth factor-${\beta}1$ expressions significantly increased. The effect of degraded silk fibroin on osteoblastogenic gene expression was confirmed by observing up-regulation of ALP activity in MG-63 cells. The finding that small fragments of silk fibroin are able to increase the expression of osteoblastogenic genes suggests that controlled degradation of silk fibroin might accelerate new bone formation.

• 한국잠사곤충학회지
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• 제50권2호
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• pp.71-75
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• 2012

실크는 생체적합성이 우수하며, 기계적 강도가 좋고, 낮은 면역 거부반응과 다양한 형태로의 성형이 가능한 장점을 갖는 천연고분자이다. 그러나 실크는 물이나 일반적인 용매에 쉽게 용해되지 않는다. 본 연구에서는 실크 피브로인의 용해조건에 따른 실크 생체막의 특성 변화를 관찰하기위하여, 실크 함유량과 실크 용해시간을 달리하여 실크 피브로인 수용액을 만들고 이를 이용하여 실크 생체막을 제작하였다. 제작된 실크 생체막의 형태, 구조, 기계적강도 등과 같은 특징을 관찰 하였다. 비록 각 실크 생체막에 함유된 피브로인의 함량이 같을 지라도 생체막의 두께와 투명도에는 커다란 차이를 보였다. 하지만 실크 피브로인 용액의 분자량과 생체막의 형태에 있어서의 변화는 거의 없었다. 본 연구는 실크 피브로인의 용해조건에 따라 실크 생체막의 유연성, 강도, 투명도 등의 다양한 특성을 조절할 수 있다는 것을 보여주었으며, 최적의 실크생체막 제작 조건을 확립하였으므로, 향후 실크를 이용한 의료용품 개발에 많은 도움이 될 것으로 생각된다.

• International Journal of Industrial Entomology and Biomaterials
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• 제30권2호
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• pp.75-80
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• 2015

The wet spinning of silk solution has attracted researchers' attention because of 1) unique properties of silk as a biomedical material and 2) easy control of the structure and properties of the regenerated silk fiber. Recently, studies have reported that different silkworm varieties produce silk with differences in the molecular weight (MW) and other mechanical properties of the regenerated silk fibroin (SF) film. In this study, we look at the effect of different Bombyx mori varieties on the wet spinning of SF. Although five regenerated SFs from different silkworm varieties have different MWs and solution viscosity, the wet spinnability and post drawing performance of regenerated SFs were not different. This result is due to low variability in the MW of the regenerated SF samples from the different silkworm varieties. In addition, unlike regenerated SF films, the mechanical properties of wet spun regenerated SF filament were not affected by silkworm variety. This result suggests that the mechanical properties of wet spun SF filament are less affected by MW than those of SF film are.

• 생약학회지
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• 제33권1호통권128호
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• pp.21-28
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• 2002

Antidiabetic effects of the acid hydrolysate of silk fibroin were investigated by oral administration to animal models for diabetes mellitus, Fibroin protein was extracted from cocoon and digested to peptides of low-molecular weight range (mainly below 3,000) and amino acids by acid hydrolysis, Feeding of the fibroin hydrolysate resulted in a significant recovering effect on reduction of body weight gain and a lowering effect on blood glucose gain in streptozotocin-induced diabetic Sprague Dawley rats (STZ rats) which were used as an insulin-dependent diabetic animal model. But the body weight and blood glucose level in C57BL/KsJ-db/db mice (db/db mice), an non-insulin-dependent diabetic animal model, were not changed significantly by the feeding, On the other hand, plasma leptin levels increased according to increased feeding amount of the hydrolysate in STZ rats and db/db mice in common, It was concluded from the results that the fibroin hydrolysate might stimulate the insulin secretion by recovering or activating pancreatic ${\beta}$ cells and result in the increased plasma leptin level. It was also deduced that the antidiabetic improvements in body weight and blood glucose gain in STZ were thought to be due to the increased insulin secretion, but in db/db mice of which the diabetic symptoms were caused by insulin resistance, the stimulated secretion of insulin was unlikely to be able to change body weight and blood glucose level significantly.

• International Journal of Industrial Entomology and Biomaterials
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• 제23권2호
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• pp.193-199
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• 2011

Silk protein and agarose are widely known as biocompatible materials in the human body. A three-dimensional (3D) scaffold composed of agarose and low-molecular- weight silk fibroin (LSF) was fabricated and examined in terms of structural characteristics and cellular responses in bone tissue engineering. This study showed that mouse pluripotent precursor cells attached to and proliferated uniformly on and within the LSF-containing 3D scaffold. Interestingly, cell proliferation and attachment was shown to be higher in a 3D scaffold containing 0.02% LSF, as compared to other LSF concentrations. The results of this study suggest that agarose-LSF scaffolds may be useful materials for tissue engineering.

• International Journal of Industrial Entomology and Biomaterials
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• 제2권1호
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• pp.15-18
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• 2001

Silk fibroin (SF) derided from the domestic silk worm, bombyx mori, is the natural protein and widely used as bio-functional materials as well as apparels. We studied the livers protective effect of SF from alcohol-induced hepatotoxicity in the alcohol preference mouse. To increase more absorption of SF in experimental animals, molecular weight of SF was lowered by 2N of HCI aqueous solution at 10$0^{\circ}C$ for 48 hrs. SF was added to liquid diet with alcohol and fed to the alcohol preference mice for 4 weeks. To assess the liver function, the concentration of alanine aminotransferase (AlT), aspartate aminotransferase (AST) and cholesterol present in either blood or liver tissue were measured. As compared with non-SF treated groups the SF-treated showed significantly low concentrations of ALT, AST, cholesterol and triacylglycerol values, respectively. Histopathological examination revealed that the extent of hepatocyte injury in the SF-treated group was reduced when it was compared with non SF-treated group. These results suggest that SF may have liver protective effects against alcohol-induced hepatotoxicity.

• 한국잠사곤충학회지
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• 제46권1호
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• pp.23-27
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• 2004

견 피브로인 가수분해물의 몇 가지 특성과 in vitro 및 in vivo에 의한 동물 인지 기능 향상효과를 알아본 결과, 다음과 같은 결과를 얻을 수 있었다. 1) 효소 가수분해 실크 피브로인 펩타이드의 분획에 있어 3가지의 분자량이 다른 분획을 제조할 수 있었다. 2) 분획 별 실크 피브로인 펩타이드의 유리 아미노산 조성은 분획간의 유의차가 나타났으며, 분획 2 및 3의 경우 활성부분을 가진 Cys, Tyr 및 Phe부분이 상당한 양을 차지하였다. 3) 대표적으로 산 및 효소 가수분해물의 핵자기공명(NMR) 법에 의한 구조적 차이는 산으로 가수분해한 저분자와 그렇치 않은 샘풀 간에는 확실한 구조적 차이에 기인한 상이한 스펙트럼을 관측할 수 있었다. 4) 분자량 별 실크 피브로인의 인지기능 향상 효과를 세포배양(in vitro)및 동물투여(in vivo)에 의해 알아본 결과, 세포배양에 의한 활성 효과는 분자량에 따라 다소 차이가 나타났으며, 그 중 분자량 500미만의 샘플군(LF)이 대조인 유발군에 비해 23.5%의 세포보호 효과가 있었다. 또한 동물(in vivo)에 의한 인지기능 향상 효과에 있어서는 보다 확실한 차이가 나타났는데, 그 중 분자량 500-1000정도의 분자량 범위의 분획물질을 10 mg/kg을 투여하였을 경우, 대조군(scopolamine)에 비하여 최고 50%까지 기억회복 효과를 나타내었다.