Figure 3.

Mass chromatograph from LC-MS analysis of peptides derived from the CM of T1 transformant with the mutated cDNA. The T1 transgenic Oc cells were transplanted into fresh MS liquid medium and incubated for 2 weeks to prepare CM. PSK-α and its analogs containing in the CM were concentrated by two steps of column chromatography and subjected to LC-MS analysis with selected ion monitoring at m/z 831 ([M—H]⁻ of [Ser⁴]PSK-α), m/z 845 ([M—H]⁻ of PSK-α), m/z 703 ([M—H]⁻ of [Ser⁴]PSK-β), and m/z 717 ([M—H]⁻ of PSK-β). The peaks eluting at 6.86, 8.00, 8.98, and 12.65 min were [Ser⁴]PSK-α, PSK-α, [Ser⁴]PSK-β, and PSK-β, respectively.