Final answer:
The observed molecular mass for Man9(GlcNAc)2 with a +3 charge state in mass spectrometry would be the monoisotopic mass divided by the charge, resulting in an m/z of approximately 3398.59.
Step-by-step explanation:
The student has asked about the molecular mass for a glycoprotein Man9(GlcNAc)2 when ionized to a +3 charge state using mass spectrometry. First, to calculate the observed mass for this molecule in its +3 charge state, we would divide the calculated monoisotopic mass by the charge number.
Given the monoisotopic mass is 10,195.76 Da (as might be inferred from similar species mentioned), the observed mass-to-charge ratio (m/z) would be 10,195.76 Da divided by 3, resulting in around 3398.59 m/z. As mass spectrometry results are often provided as m/z values in the context of charged ions, the observed m/z reflects the molecular mass divided by the charge number.