Vibrational CD studies of the solution conformation of simple alanyl peptides as a function of pH.
Vibrational CD studies of the solution conformation of simple alanyl peptides as a function of pH.
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简单丙氨酰肽溶液构象作为 pH 函数的振动 CD 研究。
DOI：
10.1002/bip.360281116
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Nafie,LA
中科院分区：
文献类型：
--
作者：
Zuk,WM;Freedman,TB;Nafie,LA
研究了甘氨酰-L-丙氨酸、L-丙氨酰甘氨酸和L-丙氨酰-L-丙氨酸在中性、高pH和低pH条件下的伸缩振动圆二色谱。在中性pH条件下，甘氨酰-L-丙氨酸中丙氨基残基的C-αH伸展所致的强阳性Vcd带在L-丙氨酰甘氨酸中不存在。与L-丙氨酸的VCD谱相比，甘氨酰-L-丙氨酸和L-丙氨酰-L-丙氨酸在pH=2时仍存在甲基伸缩的VCD正带。根据环电流机制，VCD光谱与五元CO…的存在是一致的在中性和高pH条件下，C-末端羧酸盐和多肽NH基团之间的HN分子内氢键环，以及七元COH…在低pH条件下，C-端羧基和C--O基团之间存在O--C氢键环。在N-末端丙氨基残基中，C-O基团与氨基形成氢键，与亚甲基键形成氢键。在中性pH条件下，L-丙氨基-L-丙氨基-L-丙氨酸的CH-伸缩VCD谱与中心丙氨基的两个分子内氢键构象一致。
The CH‐stretching vibrational CD (VCD) spectra of glycyl‐L‐alanine,L‐alanylglycine, andL‐alanyl‐L‐alanine have been studied at neutral, high, and low pH in D2O solution. The intense positive VCD band attributed to the CαH stretch of the alanyl residue in glycyl‐L‐alanine at neutral pH is absent inL‐alanylglycine. In contrast to the VCD spectra ofL‐alanine, the positive methine‐stretching VCD band in glycyl‐L‐alanine andL‐alanyl‐L‐alanine is still present at pH 2. Based on the ring current mechanism, the VCD spectra are consistent with the presence of a five‐membered CO … HN intramolecular hydrogen‐bonded ring between the C‐terminal carboxylate and peptide NH groups at neutral and high pH, and a seven‐membered COH … OC hydrogen‐bonded ring between the C‐terminal carboxyl OH and peptide CO groups at low pH. In the N‐terminal alanyl residue, the peptide CO group is hydrogen bonded to the NHtransto the methine bond. The CH‐stretching VCD spectra ofL‐alanyl‐L‐alanyl‐L‐alanine at neutral pH are consistent with two intramolecularly hydrogen‐bonded conformations for the central alanyl residue.