24595-69-5Relevant academic research and scientific papers
New method for the synthesis and purification of branched mPEG 2lys
González, Marianela,Grau, Ricardo J.A.,Vaillard, Santiago E.
, p. 107 - 113 (2012)
Branched PEG structures are particularly useful for the pegylation of different biomaterials. In this regard, the branched structure bearing a lysine core and two mPEG chains linked by urethane bonds (mPEG2lys) has been used for the pegylation of several important biomolecules. In this work we describe the preparation of a new functionalized mPEG featuring an alkoxy-carbonylimidazolium iodide reactive group that can be used for the urethane bonds formation required in mPEG2lys (20 kDa). The procedure for the preparation of the mPEG-alkoxy-carbonylimidazolium iodide involves the initial reaction of mPEG with N,N′-carbonylbismidazole (CDI) as phosgene equivalent, followed by alkylation with methyl iodide. The functionalized mPEG was reacted with a silylated lysine derivative affording mPEG2lys in a single step. Therefore, harmful reagents (like phosgene derivatives) are not employed, making the process safe and straightforward. A 2-step purification procedure of mPEG2lys is also presented. It is noteworthy that by following this method pure mPEG2lys was obtained with 41% isolated yield. The mPEG2lys was further converted to the N- hydroxysuccinimidyl ester by diimide activation and successfully used in the pegylation of interferon α-2a.
29Si and 13C NMR Spectra of Trimethylsilylated Amino Acids
Schraml, Jan,Kvicalova, Magdalena,Schwarzova, Iveta,Velisek, Jan
, p. 591 - 595 (2007/10/02)
The 29Si and 13C NMR chemical shifts are reported for trimethylsilyl derivatives of 25 amino acids, the majority of which occur naturally as protein constituents of foodstuffs.The 29Si chemical shifts in trimethylsilyl esters of amino acids roughly correlate linearly with the pK values of the parent amino acid.No such simple correlations were found for the shifts in the fully trimethylsilylated amino acids.The 29Si chemical shifts of various functionalities encountered fall into distinct spectral regions, but the shifts of (CH3)3SiN or (CH3)3SiOOC groups alone are not sufficiently characteristic to identify the acid but their combination is in most cases. - Keywords: 29Si NMR 13C NMR Amino acids Trimethylsilyl derivatives Chemical shifts pK values
