The CB atoms of ALA residues 14 and 18 are connected to the sulfur atom of CYS residues.

Journal of the American Chemical Society
O-Methyltransferase-Mediated Incorporation of a β-Amino Acid in Lanthipeptides.

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2.5 mM NA OlvA(BCS), 30 mM NA sodium phosphate, 0.001 % NA DSS, 90% H2O/10% D2O

2.5 mM NA OlvA(BCS), 30 mM NA sodium phosphate, 0.001 % NA DSS, 100% D2O

Delaglio, Grzesiek, Vuister, Zhu, Pfeifer and Bax