1. Human proinsulin, IV[1--3]: synthesis of a protected peptide fragment corresponding to the sequence 1--23 of the prohormone
W Danho, J Föhles Hoppe Seylers Z Physiol Chem. 1980;361(6):839-47. doi: 10.1515/bchm2.1980.361.1.839.
The synthesis of the protected peptide fragment: Boc-Phe-Val-Asn-Gln-His-Leu-Cys-(Trt)-Gly-Ser(But)-His-Leu-Val-Glu(OBut)-Ala-Le u-Tyr(But)-Leu-Val-Cys(Trt)-Gly-Glu(OBut)-Arg(HCl)-Gly-OH, corresponding to the sequence 1--23 of human proinsulin (sequence 1--23 of human insulin B chain) is described. The fragment was synthesized from two intermediate fragments: 1--16 and 17--23 and was purified by gel filtrationon Sephadex LH-20 in dimethylformamide.
2. A Facile Electrochemical Sensor Labeled by Ferrocenoyl Cysteine Conjugate for the Detection of Nitrite in Pickle Juice
Xiao-Zhen Feng, Annaleizle Ferranco, Xiaorui Su, Zhencheng Chen, Zhiliang Jiang, Guo-Cheng Han Sensors (Basel). 2019 Jan 11;19(2):268. doi: 10.3390/s19020268.
Simple and facile electrochemical sensors for nitrite detection were fabricated by directly depositing ferrocenoyl cysteine conjugates Fc[CO-Cys(Trt)-OMe]₂ [Fc(Cys)₂] or Fc[CO-Glu-Cys-Gly-OH] [Fc-ECG] on screen-printed electrodes (SPEs). The modified carbon electrodes were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Results indicated that Fc-ECG/SPE sensor showed enhanced current response and a lower overpotential than Fc(Cys)₂/SPE sensor for nitrite detection. Optimal operating conditions were estimated for nitrite detection by DPV. The concentration of nitrite showed a good linear relationship with the current response in the range of 1.0⁻50 μmol·L-1 and with 0.3 μmol·L-1 as the concentration for limit of detection. There were no interferences from most common ions. The development of this electrochemical sensor was used for nitrite detection in pickled juice with a R.S.D. lower than 2.1% and average recovery lower than 101.5%, which indicated that disposable electrochemical sensor system can be applied for rapid and precise nitrite detection in foods.
