The binding of copper ions to glycine-rich proteins (GRPs) from Cicer arietinum

• Published in: Biochimica et Biophysica Acta (BBA) - General Subjects Vol. 1722; no. 1; pp. 69 - 76
• Main Authors: Kamiya, Masakatsu, Kumaki, Yasuhiro, Nitta, Katsutoshi, Matsumoto, Takeshi, Hikichi, Kunio, Matsushima, Norio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 11.02.2005; Elsevier BV
• Subjects: Amino Acid Sequence; Cicer; Cicer - chemistry; Circular Dichroism; Copper; Copper - metabolism; Copper binding; Glycine; Glycine - metabolism; Glycine-rich protein; Histidine/glycine/tyrosine-rich domain; Ions; Ions - metabolism; Molecular Structure; NMR; Nuclear Magnetic Resonance, Biomolecular; Plant Proteins; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Binding; CD; Copper binding; NMR; Histidine/glycine/tyrosine-rich domain; Glycine-rich protein
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2004.11.012

Cicer arietinum GRP1 and GRP2 are rich in glycine interposed with histidine and tyrosine. In order to study whether or not these proteins bind Cu 2+, circular dichroism (CD) and nuclear magnetic resonance (NMR) were measured for three synthetic peptides corresponding to sections of the protein's sequences including 1, N 1Y 2G 3H 4G 5G 6G 7N 8Y 9G 10N 11, where all peptides were chemically blocked with an acetyl group at the N-terminus and an -NH 2 group at the C-terminus. The visible CD spectra for 1 showed a positive peak near 590 nm not at pH 6.0 but pH 7.4 in the presence of copper ions. The Cu 2+ binding induced a drastic change in the far-UV CD spectra, showing the occurrence of large conformation changes. In the 2D TOCSY NMR spectra at pH 7.4, the addition of small amounts of CuSO 4 caused a significant broadening of proton resonances of not only His4 but also Gly5, Asn8 and Asn11. CD titration experiment suggested that NYGHGGGNYGN including one repeat unit comprises the fundamental Cu 2+ binding unit.