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Figure 1
(a) Conformational incompatibility of the B25–B30 chain of native insulin (in white; PDB entry 1mso) with human IR. Native (hexamer-derived; PDB entry 1mso) insulin is superimposed on the invariant B9–B19 helix (in grey) in the insulin–IR complex; only the A-chain of IR-complexed insulin is shown for clarity. The TyrB26 site mutated in this work is highlighted in red. (b) Appearance of the B26-turn-like B-chain conformation in native insulin (PDB entry 1mso; white) and the insulin analogues [PheB26]-insulin (sea blue), [GlyB26]-insulin (gold), [AsnB26]-insulin (lilac), [D-ProB26]-DTI-NH2 insulin (red; Jiracek et al., 2010BB17), [D-AlaB26]-DTI-NH2 insulin (magenta; Jiracek et al., 2010BB17) and [NMeAlaB26]-insulin (blue; Jiracek et al., 2010BB17). Only the B21–B30 parts of the B-chains are colour-coded; `invariant' A-chains and B-chains are shown in pink and grey, respectively. B1(T) indicates the T-­state of native human insulin, while B1(I) denotes the so-called intermediate conformation of the B-chain N-termini. Only the B24–B26 side chains of native insulin are shown; PheB24 for [AsnB26]-insulin is shown as an example of the conservation of this side-chain conformation in all analogues shown here; a gold asterisk indicates the GlyB26 site in [GlyB26]-insulin. (c) The conformational spread of the B25–B30 insulin chain in wild-type insulin and the B26-turn- and B26-bend-containing analogues. Colour coding is as in (b). Only the B21–B30 parts of the B-chains are colour-coded; A-chains are shown in pink and B-chains in grey; a gold asterisk indicates the position of GlyB26 in [GlyB26]-insulin. The positions of the B26 side chains in wild-type insulin (TyrB26; white) and [AsnB26]-insulin (B26Asn; lilac) are also shown.

Journal logoSTRUCTURAL
BIOLOGY
ISSN: 2059-7983
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