Related Experiment Video
Updated: Mar 21, 2026
Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation
Published on: August 1, 2018
Characterization of the stereochemical configuration of lanthionines formed by the lanthipeptide synthetase GeoM
Neha Garg1, Yuki Goto2, Ting Chen3
1Roger Adams Laboratory, Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL, 61801.
Abstract:
The biosynthesis of the class II lanthipeptide geobacillin II was reconstituted in vitro. The purified precursor peptide was modified by the lanthipeptide synthetase GeoM at temperatures ranging between 37 and 80°C demonstrating the thermostability of the enzyme. Geobacillin II shares with cytolysin, haloduracin, and carnolysin a DhxDhxXxxXxxCys motif (Dhx = dehydroalanine or dehydrobutyrine) as precursor to its N-terminal A-ring. Like in these other three lantibiotics, the lanthionine in the A-ring of geobacillin II had the LL stereochemical configuration as shown by chiral gas chromatography/mass spectrometry. Various analogues of geobacillin II were produced using co-expression of mutants of the precursor peptide GeoAII and the synthetase GeoM in Escherichia coli. The findings in this study suggest that the stereochemical outcome of the A-ring in geobacillin II is not solely dependent on the peptide sequence as previously suggested for haloduracin © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 834-842, 2016.
Related Concept Videos
01:26Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
02:23SN2 Reaction: Stereochemistry
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
02:15SN1 Reaction: Stereochemistry
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
01:17Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:05Prochirality