Numerical data supporting the structural elucidation of pristinin A3 (1).

(A) Peaks unique to the extracts of strains containing pAK1 appear to be mostly derived from a single mass. (B) Many detected masses from strains containing the expression construct pAK2 appear to be derived from 2 masses. The 2 base masses were also the most abundant, making it likely these form final products, while the other masses may be incompletely processed products. (C) Observed masses for fragments of a mass of 2,703.235 Da can be matched to the SprA3 precursors. See also S11A Fig. (D) Observed masses for fragments of a peak corresponding to a monoisotopic mass of 2,553.260 Da can be matched to the SprA2 precursor. See also S11B Fig. (E) 1H and 13C NMR data for pristinin A3 (DMSO-d6, 850 MHz, 298 K, and 1H and 13C NMR data for the G24, A25, and the carboxyl-terminal ring of pristinin A3 (CD3CN:H2O 9:1, 850 MHz, 297 K)). See also S13, S14 and S15 Figs. (F) Ratio of oxidized product in samples analyzed by NMR. (G) Fragmentation data of oxidized products. A mixture of oxidized and nonoxidized fragments can be observed when the fragments do not contain the center ring structure. When the fragments do contain the center ring structure, they are always oxidized, suggesting the center ring contains the oxidation. (H) Cysteines linked to serine and threonine residues are detected after acidic hydrolysis of SprA3. Below are the predicted amino acids and their detected masses. Most of the amino acids can be detected in the chromatogram, including the cysteines linked to dehydrated serine and threonine residues. The mass of the predicted decarboxylated cysteine linked to a dehydrated threonine residue was not detected, nor were the dehydrated serine and threonine residue. However, given that these groups contain alkenes, which easily react under acidic conditions, these groups may have been degraded. (XLSX)