Secondary structure determination of ¹⁵N‐labelled human Long‐[Arg‐3]‐insulin‐like growth factor 1 by multidimensional NMR spectroscopy

Abstract

Insulin-like growth factors (IGFs) are a group of proteins that promote cell growth and differentiation. Long-[Arg-3]-IGF

Interaction of insulin-like growth factor (IGF)-I and -II with IGF binding protein-2: mapping the binding surfaces by nuclear magnetic resonance

“…(Cooke et al 1991, Sato et al 1992, more so than would be expected for variation in temperature (30 C) and pH (4·1). This was despite the fact that the 13-residue N-terminal extension and mutation of Glu 3 to Arg were reported to have little effect on the secondary structure of IGF-I (Laajoki et al 1997) IGFBP-2 were compared with the molecular mass standards thyroglobulin (669 kDa), ferritin (440 kDa), human IgG (160 kDa), transferrin (81 kDa), ovalbumin (43 kDa), myoglobin (17·6 kDa) and vitamin B12 (1·4 kDa). Absorbance was detected at 215 nm and masses are shown above (in kDa).…”

“…The thioredoxin fusion protein was removed by cleavage with EkMax enterokinase (Invitrogen) to yield IGFBP. All protein concentrations were determined by reversephase HPLC using Long-[Arg 3 ]-IGF-I (Laajoki et al 1997) as a standard.…”

Probing the disulfide folding pathway of insulin-like growth factor-I

“…It appears that the fusion protein partner and the charge reversal at position 3 of IGF-I directly affect noncovalent interactions and influence the disulfide bonding pattern. A recent structural determination of Long- [Arg 3 ]IGF-I (Laajoki et al, 1997) shows that the IGF-I part of the molecule is essentially the same as the native molecule, and that the N-terminal extension is partially structured. Significantly, this study shows that there are longrange NOEs between Phe −3 and Gly 7 and between Val −2 and Cys 6 , which places a part of the fusion-protein partner in a turn-type structure close to Cys 6 and the start of helix 1.…”

Insulin-like growth factor-I (IGF-I): Solution properties and NMR chemical shift assignments near physiological pH

“…Given the important roles of IGFs in both normal growth and development, as well as in disease states, the structures and functions of these peptides have been studied extensively using a variety of approaches, including nuclear magnetic resonance (NMR) spectroscopy [7][8][9][10][11][12][13][14][15][16][17]. Both IGF-I [7,8,[11][12][13][14][15] and IGF-II [7,9,16,17] give poor NMR spectra, characterised by many broad peaks.…”

“…Both IGF-I [7,8,[11][12][13][14][15] and IGF-II [7,9,16,17] give poor NMR spectra, characterised by many broad peaks. This is believed to arise from a combination of aggregation at the protein concentrations generally required for NMR experiments, together with conformational flexibility of the molecules.…”