[joyb]

The hydrolysis of D-glucose-1-phosphate to D-glucose and phosphate is catalysed by
alkaline phosphatase. If the enzyme catalysed reaction is conducted in H₂¹⁸O, ¹⁸O is incorporated into the phosphate product but is not incorporated into glucose. Suggest what experimental technique was used to demonstrate the incorporation of ¹⁸O into phosphate.

I'm stuck on this question- how can you specifically tell that the ¹⁸O has been incorporated into phosphate but not glucose?

[sjb]

The hydrolysis of D-glucose-1-phosphate to D-glucose and phosphate is catalysed by
alkaline phosphatase. If the enzyme catalysed reaction is conducted in H₂¹⁸O, ¹⁸O is incorporated into the phosphate product but is not incorporated into glucose. Suggest what experimental technique was used to demonstrate the incorporation of ¹⁸O into phosphate.

I'm stuck on this question- how can you specifically tell that the ¹⁸O has been incorporated into phosphate but not glucose?

How could you tell if it were incorporated into anything?

[Arkcon]

Like sjb: said, what is different about ¹⁸O?  How was anyone aware that it was even in the water used for the experiment?  This is, kinda, a very simple textbook definition.  Either you look it up, or you miss it.  We can't really "help" you find this out.  Unless you think about all the elements, that have isotopes, and how we'll tell them apart.

[Babcock_Hall]

There is an obvious answer to this question, but there is also a less obvious answer involving NMR.

[joyb]

Could you put the sample in a mass spectrometer and find that the mass of the phosphate has increased but not the glucose?

[Arkcon]

Could you put the sample in a mass spectrometer and find that the mass of the phosphate has increased but not the glucose?

That is the one I was hoping you'd come up with.  Think about Babcock_Hall:'s method now, how would that one work?

[Babcock_Hall]

I'll give you another hint.  O-18 is not itself NMR-active.