EGSLQ

• 分子结构分类: 有机化合物 - 有机酸及其衍生物 - 羧酸及其衍生物
• 英文名称: EGSLQ
• 英文别名: H-Glu-Gly-Ser-Leu-Gln-OH；(4S)-4-amino-5-[[2-[[(2S)-1-[[(2S)-1-[[(1S)-4-amino-1-carboxy-4-oxobutyl]amino]-4-methyl-1-oxopentan-2-yl]amino]-3-hydroxy-1-oxopropan-2-yl]amino]-2-oxoethyl]amino]-5-oxopentanoic acid
• 化学式: C₂₁H₃₆N₆O₁₀
• 分子量: 532.551
• InChiKey: ROMAKISHVRQMFW-XUXIUFHCSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  -6.3
• 重原子数：
  37
• 可旋转键数：
  18
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.67
• 拓扑面积：
  280
• 氢给体数：
  9
• 氢受体数：
  11

反应信息

• 作为反应物：
  描述：

  乙酸酐 、 EGSLQ 以 甲醇 、 乙醚 为溶剂， 反应 0.5h， 生成 Ac-EGSLQ
  参考文献：
  名称：

  Proinsulin C-peptide and its C-terminal pentapeptide: degradation in human serum and Schiff base formation with subsequent CO 2 incorporation

  摘要：

  Processing of human proinsulin C-peptide and its C-terminal pentapeptide in blood serum was studied using reverse-phase HPLC and electrospray mass spectrometry. The results reveal degradation of both peptides, with a longer half-life for intact C-peptide than for the C-terminal pentapeptide. Products from C-peptide degradation were not distinguishable from the peptide background, suggesting endopeptidase degradation of C-peptide. In contrast, a set of products from the C-terminal pentapeptide were identifiable and corresponded to successive losses from the N terminus, showing that the pentapeptide is degraded by aminopeptidase in serum. Consistent with this finding, a slower degradation was found for the N-acetyl-protected pentapeptide. Removal of serum proteins by acetone precipitation produced N-terminally carbamate-modified C-peptide via a Schiff base intermediate (a ketimine with acetone), to which CO2 was added and acetone removed, generating a cyclic side chain via anhydride formation. The modification was not seen with the pyroglutamate form of C-peptide, with the N-terminally acetylated C-peptide, or with a control peptide having N-terminal Phe, but was found with human C-peptide, its N-terminal tetrapeptide, and a rat C-peptide fragment (all with N-terminal Glu). Hence, the modification appears to require N-terminal Glu, but this is not the only prerequisite since the C-terminal pentapeptide and another control peptide (also starting with Glu) were not modified. A peptide aldimine Schiff base leading to CO2 incorporation was detected with formaldehyde in NaHCO3. The observation that C-peptide forms Schiff bases with ketones/aldehydes, enhancing covalent attachment of CO2, may have biological implications.

  DOI：

  10.1007/s00018-003-3117-x