Effect of Microwave Irradiation on Dipeptides and Proteins Derived from Silk During Solvation

Silkworm silk and spider silk have been attracting numerous interests.Rapid solvation of silkworm silk protein and spider silk protein without hydrolysis of peptide bonds is highly desirable.Microwave irradiation has been proposed for facile extraction of water-soluble silk protein by various liquid media.However,microwave exposure can cause hydrolysis of peptide bonds,leading to irreversible degradation of silk protein.In this study,a series of representative dipeptides and a rationally designed recombinant protein derived from silk protein is employed to investigate the efect of microwave on the stability of the peptide bonds during a long time dissolution process,i.e.,heating at 60℃in a CaCl_(2):CH_(3)CH_(2)OH:H_(2)O(1:2:8)solution.Results demonstrate that microwave irradiation imposes a minor damage and a negligible cleavage of the peptide bonds,compared with the conventional heating method.The microwave irradiation treatment suggested in this is suitable for dissolution of silk protein.It is anticipated that this approach can be developed to a commercial level commercially.

Solid phase synthesis of peptide–siRNA conjugates containing disulfde bond unit

A disulfide-modified nucleoside was designed and synthesized. After loading the modified nucleoside on controlled pore glass （CPG）, solid phase synthesis strategy was used to prepare peptide-oligonucleotide conjugates （N-3＇） containing disulfide bond unit. The 3＇-sense strand peptide-siRNA conjugate （VII） maintained good gene silencing activity, while that of the 3＇-antisense strand conjugate decreased somewhat. And the sense strand off-target effect of VII decreased remarkably.

Design, synthesis, insecticidal evaluation and molecular docking studies of cis-nitenpyram analogues bearing diglycine esters

Based on the strategies of receptor structure-guided neonicotinoid design, a series of novel cis-nitenpyram analogues bearing diglycine esters were designed and synthesized. Preliminary bioassays indicated that the insecticidal spectra of the target compounds were expanded compared with our previous work, while all the target compounds presented excellent insecticidal activities against Nilaparvata lugens and Aphis medicagini at 100 mg/L. Among these analogues, 6b showed 100% mortality against Nilaparvata lugens (LC 50 = 0.163 mg/L) and 90% against Aphis medicagini at 4 mg/L. SARs suggested that the insecticidal potency of our designed cis-nitenpyram analogues was dual-controlled by the size and species of the ester groups. The molecular docking simulations revealed that the structural uniqueness of these analogues may lead to a unique molecular recognition and binding mode compared with the previously designed compounds. Introduction of the peptide bond gave rise to more significant hydrogen bonds between the nitenpyram analogues bonding with the amino acid residues of insect nAChRs. The docking results explained the SARs observed in vitro, and shed light on the novel insecticidal mechanism of these cis-nitenpyram analogues.

PBOND:Web Server for the Prediction of Proline and Non-Proline cis/trans Isomerization

PBOND is a web server that predicts the conformation of the peptide bond between any two amino acids. PBOND classifies the peptide bonds into one out of four classes, namely cis imide （cis-Pro）, cis amide （cis-nonPro）, trans imide （trans-Pro） and trans amide （trans-nonPro）. Moreover, for every prediction a reliability index is computed. The underlying structure of the server consists of three stages： （1） feature extraction, （2） feature selection and （3） peptide bond classification. PBOND can handle both single sequences as well as multiple sequences for batch processing. The predictions can either be directly downloaded from the web site or returned via e-mail. The PBOND web server is freely available at http：//195.251.198.21/pbond.html.