Recombinant Silk Proteins with Additional Polyalanine Have Excellent Mechanical Properties.

This paper explores the structures of exogenous protein molecules that can effectively improve the mechanical properties of silkworm silk. Several transgenic vectors fused with the silkworm fibroin light chain and type 3 repeats in different multiples of the ampullate dragline silk protein 1 (MaSp1) from black widow spider with different lengths of the polyalanine motifs were constructed for this study. Transgenic silkworms were successfully obtained by piggyBac-mediated microinjection. Molecular detection showed that foreign proteins were successfully secreted and contained within the cocoon shells. According to the prediction of PONDR® VSL2 and PONDR® VL-XT, the type 3 repeats and the polyalanine motif of the MaSp1 protein were amorphous. The results of FTIR analysis showed that the content of ß-sheets in the silk of transgenic silkworms engineered with transgenic vectors with additional polyalanine was significantly higher than that of wild-type silkworm silk. Additionally, silk with a higher ß-sheet content had better fracture strength and Young's modulus. The mechanical properties of silk with longer chains of exogenous proteins were improved. In general, our results provide theoretical guidance and technical support for the large-scale production of excellent bionic silk.

Extraordinary Mechanical Properties of Composite Silk Through Hereditable Transgenic Silkworm Expressing Recombinant Major Ampullate Spidroin.

Spider dragline silk is a remarkable material that shows excellent mechanical properties, diverse applications, biocompatibility and biodegradability. Transgenic silkworm technology was used to obtain four types of chimeric silkworm/spider (termed composite) silk fibres, including different lengths of recombinant Major ampullate Spidroin1 (re-MaSp1) or recombinant Major ampullate Spidroin2 (re-MaSp2) from the black widow spider, Latrodectus hesperus. The results showed that the overall mechanical properties of composite silk fibres improved as the re-MaSp1 chain length increased, and there were significant linear relationships between the mechanical properties and the re-MaSp1 chain length (p < 0.01). Additionally, a stronger tensile strength was observed for the composite silk fibres that included re-MaSp1, which only contained one type of repetitive motif, (GA)n/An, to provide tensile strength, compared with the silk fibres that includedre-MaSp2, which has the same protein chain length as re-MaSp1 but contains multiple types of repetitive motifs, GPGXX and (GA)n/An. Therefore, the results indicated that the nature of various repetitive motifs in the primary structure played an important role in imparting excellent mechanical properties to the protein-based silk fibres. A silk protein with a single type of repetitive motif and sufficiently long chains was determined to be an additional indispensable factor. Thus, this study forms a foundation for designing and optimizing the structure of re-silk protein using a heterologous expression system.

[Study on the hemostatic effects in raw and charred Mongolian drug Agi and its mechanism].

OBJECTIVE: To observe the effects of raw and charred Agi on hemostasis and its mechanism. METHODS: The rabbit bleeding time was measured by traumatic hemorrhage test, and the clotting time was measured by tube test. The rabbit prothrombin time (PT), activated partial thormboplastia time (APTT), thrombin time (TT), fibrinogen (FIB), plasma recalcification time (PRT), euglobulin lysis time (ELT), max platelet aggregation rate (MPAR) were measured by solidification method, turbidimetry and tube test to analyze the effects of raw and charred Agi on rabbit coagulation-fibrinolysis system and platelet function. RESULTS: The medium doses and high doses of raw Agi groups, all of the groups of charred Agi decreased rabbit BT obviously (P<0.01 or P<0.05); all of the groups of raw and charred Agi declined rabbits CT (P<0.01 or P<0.05). All of the doses groups of raw and charred Agi had no apparent influences on PT (P>0.05); the high dose of raw Agi group and all of the groups of charred Agi decreased APTT apparently (P<0.01 or P<0.05) and prolonged ELT (P<0.01 or P<0.05); the high doses groups of raw and charred Agi decreased TT apparently (P<0.01 or P<0.05); the medium and high doses groups of charred Agi increased FIB obviously (P<0.01 or P<0.05); the high doses group of charred Agi showed the decreased PRT significantly (P<0.05) and increased MPAR obviously (P<0.01). CONCLUSIONS: Raw Agi can play its role in hemostasis and coagulation by affecting the intrinsic pathway of coagulation and fibrinolytic system. These effects are inhanced after processing drugs; moreover, the charred Agi could increase FIB and MPAR with promoting more in blood coagulation.