Hydrophobic Core around Tyrosine for Human Endothelin-1 Investigated by Photochemically Induced Dynamic Nuclear Polarization Nuclear Magnetic Resonance and Matrix-Assisted Laser Desorption Ionization
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- 作者：Hiroyuki Takashima ; Haruhiko Tamaoki ; Naoki Teno ; Yoshinori Nishi ; Susumu Uchiyama ; Kiichi Fukui ; and Yuji Kobayashi
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：November 9, 2004
- 年：2004
- 卷：43
- 期：44
- 页码：13932 - 13936
- 全文大小：211K
- 年卷期：v.43,no.44(November 9, 2004)
- ISSN：1520-4995
文摘
Human endothelin-1 (ET-1) is a potent cardiovascular bioactive peptide. Its activity is basedon the C-terminal residues, e.g., Trp 21 in particular. Recently, we reported an NMR solution structureof ET-1, which has a C-terminal hydrophobic core around Tyr 13. This C-terminal conformation does notagree with a previously reported X-ray crystal structure. To clarify the discrepancy, we performed photo-CIDNP NMR in combination with MALDI-TOF MS. The photo-CIDNP results revealed that the Tyr 13aromatic ring is concealed in a hydrophobic interaction. MALDI-TOF MS experiments showed this is anintramolecular interaction in monomeric form, which is also supported by sedimentation analysis andtwo-dimensional NMR cross-peak line shapes. Thus, we confirmed the intramolecular hydrophobic corearound Tyr 13 in aqueous solution, which agrees with the solution structure. The C-terminal conformationaldiscrepancy between the solution and crystal was caused by the intermolecular hydrogen bond betweenTyr 13 of one molecule and Asp 8 of the other in a dimer-like formation of crystalline ET-1. On the otherhand, we indicated that endothelin-3, another isoform of the endothelin, has an apparent self-associationequilibrium under the same condition in which three tyrosines participate.