Inventory of ‘slow exchanging’ hydrogen atoms in human proinsulin and its derivatives: Observations on the mass spectrometric analysis of deuterio-proteins in D2O

Conformational transmission in proinsulin and its derivatives: A study using H/D exchange

“…This conclusion is similar to that deduced by the systematic studies of Weiss and coworkers using NMR [4] which has recently led to the description of finer details of the molecule and in particular of the structure of the C-A junction [10]. Some aspects of these findings are compared with the results of H-D exchange experiments described in this paper and reported elsewhere for the human system [8].…”

“…While, the domain containing the A and B chains of insulin has 23 (±1) slow exchanging hydrogen atoms and has very similar exchange kinetics as found for mature human insulin [8]. A similar conclusion was also deduced by NMR studies [4,10].…”

“…The proinsulin numbering system is used above and the N-terminal methionine is considered as residue zero. earlier paper [8] from an unpublished work [9], lacks necessary resolution in and around the C-chain domain but in general shows that the C-chain is largely unstructured while its insulin moiety has a similar structure to that of the mature hormone. This conclusion is similar to that deduced by the systematic studies of Weiss and coworkers using NMR [4] which has recently led to the description of finer details of the molecule and in particular of the structure of the C-A junction [10].…”

“…Using recombinant human proinsulin, and its derivatives, in which all the exchangeable hydrogen atoms had been replaced with deuterons, we have recently shown by H/D exchange technique that its C-peptide domain, comprising 30 peptide bonds, is relatively unstructured, containing only four slow exchanging hydrogen atoms [8]. While, the domain containing the A and B chains of insulin has 23 (±1) slow exchanging hydrogen atoms and has very similar exchange kinetics as found for mature human insulin [8].…”

“…Its X-ray structure, the ribbon diagram of which is included in our 2 These observations underpin the protocol used in the present paper to study H-D exchange in 0.5 M acetic acid, pH 2.8. Further elaboration on the use of low pH for the study is provided in Section 2.1.1 of our previous paper [8]. (1) and its tryptic products C-peptide-KR (2), M-insulin-RR (3), R-C-peptide-KR (4) and M-insulin-R (5).…”