Can Isopropyl β-D-1-thiogalactopyranoside be degraded into either 1-deoxy-galactose or just galactose?
I'm not sure if I understood your question correctly, and my thought is based on this assumed reaction:

Your indication of a resolution of about 1.8 Å reads like the data were collected by Cu K$\alpha$ radiation, rather than by Mo K$\alpha$.  If sulfur was split off from your molecule, than (even more with softer Cu than Mo X-rays) this should have decreased a lot the contribution of anomalous scattering in the X-ray data, as CHO's atomic scattering factors -- in comparsion -- are mainly described by $f'$, and not so much about $f''$. What about looking on value .and. esd of the Flack parameter of your model for your new product, compared to a &quot;typical / reference&quot; model of IPTG?
(By the way, Howard Flack passed away just at the beginning of this year.)