Logo image
Back
Carbon 13 as a Probe of Helix Formation in Semisynthetic Ribonuclease-s
Journal article   Open access   Peer reviewed

Carbon 13 as a Probe of Helix Formation in Semisynthetic Ribonuclease-s

Irwin M. Chaiken
The Journal of biological chemistry, v 249(4), pp 1247-1250
25 Feb 1974
DOI: https://doi.org/10.1016/S0021-9258(19)42967-0
PMID: 4814342
url
https://doi.org/10.1016/s0021-9258(19)42967-0View
Published, Version of Record (VoR) Open
url
https://doi.org/10.1016/S0021-9258(19)42967-0View
Published, Version of Record (VoR) Open

Abstract

An enzymically active analogue of semisynthetic ribonuclease-s' (the noncovalent complex of synthetic-(1–15) (corresponding to residues 1 through 15 of bovine pancreatic ribonuclease-A) and native ribonuclease-S-(21–124) (containing residues 21 through 124 of ribonuclease-A)) was prepared with specific carbon 13-enriched glycine in place of the normally occurring alanine at position 6. This material was synthesized in a manner such that half of the molecules contain 13C enrichment only at the carbonyl carbon of glycine 6, while the other half contain enrichment only at the α carbon. Carbon 13 nuclear magnetic resonance (13C NMR) spectroscopic analysis of this ribonuclease-s' analogue, as as well as of the isolated [Gly6-13C0,α]synthetic-(1–15) peptide component of the complex, allow the detection of singlet resonances for both the carbonyl and α carbon atoms in the two states. The chemical shifts of both of these resonances exhibit downfield transitions in going from the isolated, and disordered, synthetic fragment to the folded semisynthetic complex. In addition, the Cα resonance broadens significantly during the folding process, while that for C0 broadens only very little. These chemical shift and line width transitions are interpreted as due to the formation of the ribonuclease-s' NH2-terminal α helix, which includes position 6. Taken together with previous experiments, the results indicate that 13C NMR can be used to monitor helix formation at an individual amino acid locus in proteins.

Metrics

9 Record Views
22 citations in Web of Science

Details

Logo image