Amino Acids In Silk Research Articles

Effects of Silk Amino Acids on Hair

Purpose: To investigate how silk amino acids affect the hair by applying them to bleached hair.Methods: A silk amino acid formulation was prepared by adding 0, 3, 6, and 9 g of silk amino acid content. The prepared formulation was applied to bleached hair. To determine the change in hair brightness, the L* value was measured using a colorimeter. Additionally, the hair’s tensile strength, absorbance using methylene blue, and gloss were measured to determine whether amino acids affect bleached hair. Then we performed a comparison of data between the sample hair with the formulation agent containing silk amino acid and damaged hair.Results: Regarding brightness, the L* value for each sample increased as compared with that of damaged hair. Additionally, the brightness increased as the silk amino acid content increased. Moreover, the tensile strength of all samples with perm-base and silk amino acid added increased as compared with the damaged hair. The tensile strength also increased as the silk amino acid content increased. The absorbance of all samples with perm-base and silk amino acid added decreased as compared with that of damaged hair, and as the silk amino acid content increased, the absorbance also decreased. Regarding gloss, the gloss of the samples with perm-base decreased as compared with that of damaged hair. However, as the silk amino acid content increased, the gloss also increased.Conclusion: There were differences in brightness, absorbance, and gloss between damaged hair and bleached hair with silk amino acid, suggesting that silk amino acids have an effect on damaged hair. In the future, studies investigating on whether various natural ingredients affect damaged hair are warranted.

An atomistic scale simulation study of structural properties in the silk-fibrohexamerin complex.

The use of Bombyx mori silk fibroin in composite materials has been extensively explored in many studies, owing to its remarkable mechanical properties. Recently, the N-glycan-engineered P25 protein was utilized to improve the mechanical properties of silk. However, the mechanism by which N-glycan-engineered P25 protein enhances the mechanical properties of silk remains unclear. This study analyzed the interaction between the P25 protein and silkworm silk using quantum mechanics/molecular mechanics multiscale simulations and discovered stronger hydrogen bonding between the amorphous domain and the P25 protein. The results confirmed that glycoengineering of the mannose molecule in N-glycan in orders of three, five, and seven increased the hydrogen bonding of the amorphous structures. However, P25 has fewer binding interactions with the crystalline domain. Silk amino acids and mannose molecules were analyzed using QM simulations, and hydroxyl and charged amino acids in the amorphous domains were found to have relatively higher reactivity with mannose molecules in N-glycans than basic and aliphatic amino acids in the crystalline domain. This study demonstrates how the N-glycan-engineered P25 protein can improve the mechanical properties of silk fibroin and identifies a key factor for N-glycan-engineered proteins.

Development and processing of novel heparin binding functionalized modified spider silk coating for catheter providing dual antimicrobial and anticoagulant properties

Tailored surface coatings have been used for decades to improve material performance in blood. Among different approaches, heparin based biomedical coatings have found great success in the commercial catheter market. However, they have their own limitations. Coating of a vascular device with a heparin binding peptide (HBP), which can sequester the circulating heparin, presents numerous advantages over both systemic heparin therapy and direct heparin bound surfaces. Embedding HBP in a silk biopolymer provides the mechanical integrity necessary under dynamic flow conditions to both insert the catheter and maintain proper blood flow. Furthermore, due to the similarity in structure of HBP with antimicrobial peptides, it is predicted that the fusion protein will also show antimicrobial property, a critical and unique aspect to combat catheter related blood stream infections and extend the longevity of hemodialysis catheters. To assess this hypothesis, a recombinant fusion protein (S4H4) containing both silk amino acid motifs and HBP was assessed as a coating on a silicone surface. After validating that, the protein was deposited on the surface via XPS, Raman spectroscopy, ATR and SEM imaging, antimicrobial and anticoagulant activities were evaluated. The coating was able to prevent not only planktonic bacterial growth but also prevented the growth of a biofilm. Finally, the coating had both antibacterial and anticoagulant effect simultaneously. This study proves the successful production of a silk-based biopolymer that can be embedded with a heparin-binding functionality to create a dual functional device coating that can prevent infection and thrombosis together.

A mixture of mulberry and silk amino acids protected against D-galactosamine induced acute liver damage by attenuating oxidative stress and inflammation in HepG2 cells and rats.

The liver is an important organ for the removal of toxins and utilization of nutrients. The present study then investigated whether a mixture of mulberry water extracts and silk amino acids protected against acute liver damage in rats induced by intraperitoneal injection of D-galactosamine and the action mechanism. D-galactosamine injection is widely used to develop experimental animal models of acute hepatic disease. In the present study, male Sprague-Dawley rats received intraperitoneal injection of D-galactosamine followed by 200 and 600 mg/kg body weight (BW) of mulberry extracts and silk amino acids (1:3, w/w; MS1:3-L and MS1:3-H), the same amounts of MS with different ratios (1:5, w/w; MS1:5-L and MS1:5-H), and 600 mg/kg bw cellulose (control) for 1 week. The normal-control group received an injection of saline instead of D-galactosamine with the same diet as the control group. D-galactosamine injection (control rats) increased serum ALT, AST and γ-GPT levels, indicating the induction of acute liver damage. The control rats also exhibited reduced glycogen depositions, which contributed to increasing fat synthesis from glucose and elevated serum triglyceride levels. Oxidative stress and inflammation in the liver of the control increased in response to the decreasing antioxidant activity and mRNA expression and increasing TNF-α expression, respectively. Both MS1:3 and MS1:5 reduced serum ALT, AST and γ-GPT levels to ameliorate liver damage. MS1:3 reduced oxidative stress by increasing the activity and expression of antioxidant enzymes, whereas MS1:5 decreased the expression TNF-α in the liver. MS1:3 and MS1:5 improved the necrosis of hepatocytes in H&E staining, which was associated with increased glycogen deposition in PAS staining. MS1:5 had better effects on glycogen accumulation. In conclusion, MS1:3 and MS1:5 can be used as therapeutic agents for acute liver damage.

실크아미노산 섭취가 여자 중·고등학교 축구선수의 하지 근 기능에 미치는 영향

The purpose of this study was to find out the effect of the eight-week intake of silk amino acids on the muscular functions of the lower limb of female middle and high school soccer players. To achieve the purpose of the study, 20 female soccer players attending Chungju Y Middle School (3grade) and Y High School (1 to 3 grade) were selected as radio sampling methods and divided into experimental groups (10 intake silk) and comparative groups (10 intake placebo). The two groups lived in a dormitory during the intake period, ate the same nutrition, and homogenized the amount of exercise through team training. In the pre-test before the experiment, the subjects were tested for joint continuity to measure their lower extremities’ muscular functions, and eight weeks later, post-testing was carried out in the same way as the pre-test. Data processing was calculated by using the SPSS 12.0 statistics program and the Mann-Whitney U test was used to determine the mean difference between variables. The results showed a significant improvement in maximum muscle strength and muscle endurance compared to those who took placebo in groups that consumed silk amino acids for eight weeks. Therefore, it can be suggested that the eight-week intake of silk amino acids will improve the root function of female middle and high school soccer players and, by extension, provide effective nutrition for soccer players.

Silk physico-chemical variability and mechanical robustness facilitates intercontinental invasibility of a spider

There are substantive problems associated with invasive species, including threats to endemic organisms and biodiversity. Understanding the mechanisms driving invasions is thus critical. Variable extended phenotypes may enable animals to invade into novel environments. We explored here the proposition that silk variability is a facilitator of invasive success for the highly invasive Australian house spider, Badumna longinqua. We compared the physico-chemical and mechanical properties and underlying gene expressions of its major ampullate (MA) silk between a native Sydney population and an invasive counterpart from Montevideo, Uruguay. We found that while differential gene expressions might explain the differences in silk amino acid compositions and protein nanostructures, we did not find any significant differences in silk mechanical properties across the populations. Our results accordingly suggest that B. longinqua’s silk remains functionally robust despite underlying physico-chemical and genetic variability as the spider expands its range across continents. They also imply that a combination of silk physico-chemical plasticity combined with mechanical robustness might contribute more broadly to spider invasibilities.

Effect of long-term cadmium and copper intoxication on the efficiency of ampullate silk glands in false black widow Steatoda grossa (Theridiidae) spiders

The aim of the study was to compare cellular effects of xenobiotic cadmium and biogenic copper in ampullate silk glands of false black widow Steatoda grossa spider after long-term exposure via ingestion under laboratory conditions. Both the level of selected detoxification parameters (glutathione S-transferase, catalase, and the level of total antioxidant capacity) and degree of genotoxic changes (comet assay) were determined in the silk glands. Additionally the contents of selected amino acids (L-Ala, L-Pro, L-His, L-Phe, DL-Ile, and DL-Asn) in the hunting webs produced by spiders of this species were assessed. The ability of S. grossa females to accumulate cadmium was higher than that for copper. Long-term exposure of spiders to copper did not change the level of detoxification parameters, and the level of DNA damage in the cells of ampullate silk glands was also low. Cadmium had a stronger prooxidative and genotoxic effect than copper in the cells of the analyzed silk glands. However, regardless of the type of metal used, no significant changes in the level of amino acids in silk were found. The obtained results confirmed the effectiveness of metal neutralization mechanisms in the body of the studied spider species, which results in the protection of the function of ampullate silk glands.

The Combination of Mulberry Extracts and Silk Amino Acids Alleviated High Fat Diet-Induced Nonalcoholic Hepatic Steatosis by Improving Hepatic Insulin Signaling and Normalizing Gut Microbiome Dysbiosis in Rats.

Mulberry water extracts (MB) and silk amino acids (SA) are reported to improve oxidative stress and inflammation, respectively. We hypothesized whether the mixture of mulberry water extracts and silk amino acids can alleviate nonalcoholic fatty liver disease (NAFLD) induced by high fat diets. Male Sprague Dawley rats were orally provided with high fat diets containing different ratios of MB and SA (1:3, MS1:3, or 1:5, MS1:5) or cellulose (the disease-control) for 12 weeks. Rats had 200 or 600 mg/kg bw of MS1:3 and MS1:5 (MS1:3-L, MS1:3-H; MS1:5-L, and MS1:5-H). Rats in the normal-control group were fed the 20% fat diet with cellulose. Disease-control rats exhibited much greater triglyceride (TG) deposition in the liver than the normal-control rats along with increased body weight gain, visceral fat mass, serum concentrations of cholesterol, triglyceride and nonesterified fatty acid (NEFA), and insulin resistance. Disease-control rats also had liver damage with increased oxidative stress and inflammation compared to the normal-control rats. MS1:3-H and MS1:5-H were found to have greater hepatic glycogen accumulation and decreased hepatic TG, insulin resistance, and dyslipidemia, with MS1:5-H being similar to the normal-control. MS1:3-H alleviated oxidative stress with lower hepatic lipid peroxide compared to MS1:5-H whereas MS1:5-H ameliorated inflammation and hepatocyte damage better than MS1:3-H. Both MS1:3-H and MS1:5-H potentiated hepatic insulin signaling (pAkt⟶pACC) and reduced the mRNA expression of TG synthesis genes mRNA (FAS and SREBP-1c). In the gut microbiome MS1:3-H elevated the ratio of Bacteroidales to Clostridiales in the cecum better than MS1:5-H but MS1:5-H reduced the proinflammatory Turicibacterales. In conclusion, both MS1:3-H and MS1:5-H prevented liver damage induced by high fat diets, mainly by suppressing oxidative stress and inflammation, respectively. MS1:3 and MS1:5 might be used as therapeutic agent for NAFLD.

Red mulberry fruit aqueous extract and silk proteins accelerate acute ethanol metabolism and promote the anti‑oxidant enzyme systems in rats.

Red mulberry (Morusalba) fruit is rich in anthocyanins, and mulberry leaves are used by silk worms to make silk protein. We determined that the water and ethanol extract of mulberry fruit and silk amino acids accelerated ethanol degradation and suppressed temporal cognitive dysfunction in acute alcohol administered rats. The mechanism was explored in rats with acute oral administration of silk protein and mulberry fruit extracts. Rats were given 0.3g of dextrin (control) and water extract (WMB) and ethanol extract of mulberry (EMB), silk protein hydrolysates (SKA), and a commercial product (positive‑control) based on body weight. After 30min, rats were administered 3g ethanol/kg body weight and serum ethanol and acetaldehyde levels were measured. After 3h movements were measured with a video tracking system and at 5h cognitive function was measured by Ymaze test. WMB contain much higher rutin, luteolin and quercetins than EMB. In SKA rats, serum alcohol concentrations slowly increased until 60min, but were markedly elevated until 120min. However, WMB rats exhibited rapidly increased serum alcohol levels until 60min and showed the lowest peak of serum alcohol levels, indicating the highest degradation of alcohol. The patterns of serum acetaldehyde levels were similar to those of serum ethanol levels but WMB was more effective for reducing serum acetaldehyde levels than serum ethanol levels. WMB was most effective for increasing mRNA expression of alcohol dehydrogenase and acetaldehyde dehydrogenase. WMB and SKA decreased lipid peroxides by increasing activities of SOD and GSH‑Px in the liver and they also reduced pro‑inflammatory cytokines such as tumor necrosis factor‑α and interleukin‑6. WMB and SKA exerted better anti‑oxidant effects than the positive‑control. WMB containing higher flavonoids reduced pro‑inflammatory cytokines better than SKA. In conclusions, both WMB and SKA might reduce acute alcohol‑induced hangover and liver and brain damage by lowering serum alcohol and acetaldehyde levels.

Evidence of Decoupling Protein Structure from Spidroin Expression in Spider Dragline Silks.

The exceptional strength and extensibility of spider dragline silk have been thought to be facilitated by two spidroins, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2), under the assumption that protein secondary structures are coupled with the expressed spidroins. We tested this assumption for the dragline silk of three co-existing Australian spiders, Argiope keyserlingi, Latrodectus hasselti and Nephila plumipes. We found that silk amino acid compositions did not differ among spiders collected in May. We extended these analyses temporally and found the amino acid compositions of A. keyserlingi silks to differ when collected in May compared to November, while those of L. hasselti did not. To ascertain whether their secondary structures were decoupled from spidroin expression, we performed solid-state nuclear magnetic resonance spectroscopy (NMR) analysis on the silks of all spiders collected in May. We found the distribution of alanine toward β-sheet and 3,10helix/random coil conformations differed between species, as did their relative crystallinities, with A. keyserlingi having the greatest 3,10helix/random coil composition and N. plumipes the greatest crystallinity. The protein secondary structures correlated with the mechanical properties for each of the silks better than the amino acid compositions. Our findings suggested that a differential distribution of alanine during spinning could decouple secondary structures from spidroin expression ensuring that silks of desirable mechanical properties are consistently produced. Alternative explanations include the possibility that other spidroins were incorporated into some silks.

Spider web and silk performance landscapes across nutrient space.

Predators have been shown to alter their foraging as a regulatory response to recent feeding history, but it remains unknown whether trap building predators modulate their traps similarly as a regulatory strategy. Here we fed the orb web spider Nephila pilipes either live crickets, dead crickets with webs stimulated by flies, or dead crickets without web stimulation, over 21 days to enforce spiders to differentially extract nutrients from a single prey source. In addition to the nutrients extracted we measured web architectures, silk tensile properties, silk amino acid compositions, and web tension after each feeding round. We then plotted web and silk “performance landscapes” across nutrient space. The landscapes had multiple peaks and troughs for each web and silk performance parameter. The findings suggest that N. pilipes plastically adjusts the chemical and physical properties of their web and silk in accordance with its nutritional history. Our study expands the application of the geometric framework foraging model to include a type of predatory trap. Whether it can be applied to other predatory traps requires further testing.

Supplementation with Silk Amino Acids improves physiological parameters defining stamina in elite fin-swimmers.

BackgroundPrevious animal study has shown that supplementation with silk amino acid hydrolysate (SAA) increases stamina in mice. The presented study was the first formal evaluation of the influence of SAA supplementation on parameters defining physiological fitness level in humans.MethodsIt was a randomized controlled trial with a parallel-group design on elite male fin-swimmers. The experimental group was supplemented with 500 mg of SAA per kg of body mass, dissolved in 250 ml of a Carborade Drink®; the control group with Carborade Drink® alone; 3 times a day, 30 minutes prior to the training session.ResultsChanges discerned in the experimental group were more pronounced than those observed in the control group. For example, the change in the serum lactic acid concentration observed in the experimental group was sevenfold less than in the control group [21.8 vs. -3.7 L% for the control and experimental groups, respectively]. An analysis of a lactate profile as a function of a maximal swimming velocity exposed a statistically significant positive shift in the swimming velocity of 0.05 m/s, at the lactate concentration of 4 mmol/L in the experimental group. There was also a positive, although statistically insignificant, increase of 2.6 L% in serum testosterone levels in the experimental group.ConclusionsThis study showed that a 12-day SAA supplementation combined with an extensive and rigorous training schedule was sufficient to increase an aerobic stamina. However, this phenomenon was associated with an augmented level of muscular damage (an increased level of creatine phosphokinase in the experimental group).

Nutrient-Mediated Architectural Plasticity of a Predatory Trap

BackgroundNutrients such as protein may be actively sought by foraging animals. Many predators exhibit foraging plasticity, but how their foraging strategies are affected when faced with nutrient deprivation is largely unknown. In spiders, the assimilation of protein into silk may be in conflict with somatic processes so we predicted web building to be affected under protein depletion.Methodology/Principal FindingsTo assess the influence of protein intake on foraging plasticity we fed the orb-web spiders Argiope aemula and Cyclosa mulmeinensis high, low or no protein solutions over 10 days and allowed them to build webs. We compared post-feeding web architectural components and major ampullate (MA) silk amino acid compositions. We found that the number of radii in webs increased in both species when fed high protein solutions. Mesh size increased in A. aemula when fed a high protein solution. MA silk proline and alanine compositions varied in each species with contrasting variations in alanine between the two species. Glycine compositions only varied in C. mulmeinensis silk. No spiders significantly lost or gained mass on any feeding treatment, so they did not sacrifice somatic maintenance for amino acid investment in silk.Conclusions/SignificanceOur results show that the amount of protein taken in significantly affects the foraging decisions of trap-building predators, such as orb web spiders. Nevertheless, the subtle differences found between species in the association between protein intake, the amino acids invested in silk and web architectural plasticity show that the influence of protein deprivation on specific foraging strategies differs among different spiders.

Variation in protein intake induces variation in spider silk expression.

BackgroundIt is energetically expensive to synthesize certain amino acids. The proteins (spidroins) of spider major ampullate (MA) silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved.Methodology/Principal FindingsWe fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake.ConclusionsOur results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact mechanics.

Tyrosine-fortified silk amino acids improve physical function of Parkinson’s disease rats

Physical function-improving effects of a silk amino acid preparation (SAA) in Parkinson’s disease (PD) model rats were investigated. 6-Hydroxydopamine (6-OHDA, 8 μg)+ascorbic acid (0.6 μg) was injected into right medial forebrain bundle of 8-week-old Sprague-Dawley rats to induce PD, and SAA (50, 160, or 500 mg/kg) was orally administered for 30 days. On day 15 and 30, behavioral abnormalities, neuronal loss, and dopamine and its metabolites were analyzed. Injection of 6-OHDA impaired pole test performances, which were markedly improved by treatment with SAA. Increased using rate of ipsilateral (normal) forelimb in cyclinder test and apomorphine (0.05 mg/kg)-induced circling behavior of PD rats were remarkably corrected by the compounds. In addition, 6-OHDA-induced loss of neurons as well as decreases in dopamine and its metabolites were significantly attenuated by SAA. The results indicate that SAA preserves movement function of PD model animals by protecting dopamine neurons against 6-OHDA neurotoxicity.

Silk Amino Acids Improve Physical Stamina and Male Reproductive Function of Mice

The effects of a silk amino acid (SAA) preparation on the physical stamina and male reproductive function of mice were investigated. Eight-week-old male ICR mice (29-31 g) were orally administered SAA (50, 160 or 500 mg/kg) for 44 d during 30-min daily swimming exercise. The mice were subjected to a weight-loaded (5% of body weight) forced swimming on the 14th, 28th and 42nd day to determine maximum swimming time, and after a 2-d recovery period (treated with SAA without swimming exercise), parameters related to fatigue and reproductive function were analyzed from blood, muscles and reproductive organs. Repeated swimming exercise increased the maximum swimming time to some extent, in spite of a marked reduction in body weight gain, and SAA further enhanced the stamina in a dose-dependent manner. Forced swimming exercises increased blood parameters of tissue injury, but depleted blood glucose and tissue glycogen, which were substantially prevented by SAA treatment. In addition, SAA significantly reduced the muscular thiobarbituric acid-reactive substances and blood corticosterone content increased by forced swimming. Swimming exercise decreased the blood testosterone level, which was recovered by SAA, leading to enhanced sperm counts. These combined results indicate that SAA not only enhances physical stamina by minimizing damage to tissues, including muscles, as well as preventing energy depletion caused by swimming stress, but also improves male reproductive function by increasing testosterone and sperm counts.

The effects of wind on trap structural and material properties of a sit-and-wait predator

Numerous terrestrial invertebrates use secretions produced by themselves to build prey traps. Potentially, the structural as well as material properties of such constructions will reflect adaptations to wind disturbances, but most relevant studies only focus on trap structural characteristics. In this study, we examined how wind disturbances affected the structural and material properties of prey traps constructed by a sit-and-wait Araneae predator. We first compared web structures and major ampullate (MA) silk properties of 2 Cyclosa spider species inhabiting seashores and forests to see whether these properties reflected the habitat-specific wind disturbances these spiders experienced. The MA silks of the seashore-dwelling Cyclosa mulmeinensis were significantly thicker and contained higher percentage of glycine and lower glutamine. Congruent with such amino acid variation pattern were higher ultimate tension and breaking energy of C. mulmeinensis MA silks. However, despite that this species’ silks were relatively glycine rich and glutamine poor, they also showed greater extensibility. Compared with webs built by Cyclosa ginnaga, those built by C. mulmeinensis were composed of fewer drag-reducing silk threads but were stiffer. In a laboratory manipulation, MA silk amino acid composition and diameter did not differ between C. mulmeinensis receiving different levels of wind. However, those receiving persistent wind disturbances built smaller webs composed of fewer but stronger MA silks to reduce drag and prevent the web from damage. Orb web spiders inhabiting areas with different levels of wind disturbances exhibit variation and plasticity in structural and material properties of prey traps. Furthermore, the silk property plasticity does not have to involve alterations of amino acid composition.

Studies on the distribution of amino acids in silk.(IV) Comparison of amino acids of domesticated sikworm fibroin with those of wild silkworm one.

Studies on the distribution of amino acids in silk.(IV) Comparison of amino acids of domesticated sikworm fibroin with those of wild silkworm one.

Studies on the Distribution of Amino Acids in Silk

Studies on the Distribution of Amino Acids in Silk

Studies on the Distribution of Amino Acids in Silk

Studies on the Distribution of Amino Acids in Silk