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52 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYThe extract from S. chromofuscus %u0394M8DH was purified, and several fractions were collected. Based on the fractions obtained from prep - HPLC, two samples with potentially high purity were identified, as they each showed a single peak in the HPLC analysis. These fractions were subjected to mass spectrometry analysis. The fraction with a retention time of 5.52 minutes displayed a mass of 461.2869, which corresponds to the mass of herboxidiene [+Na+]. The exact mass of herboxidiene [+Na+] is 461.2874, which is only slightly different. Additionally, the fraction with a retention time of 6.74 minutes showed a mass of 415.2823. Two potential structures for this compound were proposed. The first structure is formed with [-H2O] group due to the absence of 8DH domain activity, with an exact mass of 415.2819, indicating no PKS tailoring modification (Fig. 7ii). The second possible structure is a linear herboxidiene polyketide intermediate, lacking the [-H2O] group due to the presence of 8DH domain activity, with a mass of 415.2819, and also showing no PKS tailoring modification (Fig. 7iii).