Anderegg R J, Betz R, Carr S A, Crabb J W, Duntze W
Department of Chemistry, University of Maine, Orono 04469.
J Biol Chem. 1988 Dec 5;263(34):18236-40.
Mating type a cells of the yeast Saccharomyces cerevisiae produce a mating hormone, the a-factor, that we have previously characterized as a very hydrophobic, modified dodecapeptide (Betz, R., Crabb, J. W., Meyer, H. E., Wittig, R., and Duntze, W. (1987) J. Biol. Chem. 262, 546-548). We have investigated the molecular structure in detail using mass spectrometry and proton NMR spectrometry of the intact hormone and authentic component molecules. Tandem mass spectrometry confirms the previously determined peptide sequence of the hormone and shows that it contains additional structural components with masses of 205 and 15 daltons. These were identified by proton NMR and mass spectrometry as a farnesyl (C15H25) residue and a terminal methyl ester group. The farnesyl moiety is attached to the sulfur atom of the carboxyl-terminal cysteine residue, as revealed by NMR of synthetic S-farnesyl cysteine methyl ester. The stereochemical configuration of the farnesyl moiety was determined to be trans,trans by comparison of gas chromatography retention times, mass spectra, and NMR spectra with those of standards. These results define the structure of a-factor as: (Sequence: see text). Replacement of the farnesyl by a methyl group leads to a partial reduction in specific biological activity of the a-factor, whereas hydrolysis of the carboxyl-terminal methyl ester causes a complete loss of activity.
酿酒酵母的a型交配细胞产生一种交配激素，即a因子，我们之前已将其鉴定为一种非常疏水的修饰十二肽（贝茨，R.，克拉布，J.W.，迈耶，H.E.，维蒂希，R.，和邓茨，W.（1987年）《生物化学杂志》262卷，546 - 548页）。我们使用完整激素和真实成分分子的质谱和质子核磁共振光谱详细研究了其分子结构。串联质谱证实了该激素先前确定的肽序列，并表明它包含质量为205和15道尔顿的额外结构成分。通过质子核磁共振和质谱将这些成分鉴定为法尼基（C15H25）残基和末端甲酯基团。如合成的S - 法尼基半胱氨酸甲酯的核磁共振所示，法尼基部分连接到羧基末端半胱氨酸残基的硫原子上。通过将气相色谱保留时间、质谱和核磁共振光谱与标准品进行比较，确定法尼基部分的立体化学构型为反式，反式。这些结果确定了a因子的结构为：（序列：见正文）。用甲基取代法尼基会导致a因子的特定生物活性部分降低，而羧基末端甲酯的水解会导致活性完全丧失。
