Alternatively, you could also call it the conversion of a hydroxyl group to a phosphate group. Just like in that scheme above, we could call it a conversion of a hydroxyl group to a methoxy group.
@barlop I think it's hard to argue that there isn't a phosphate group in ADP. That would be like claiming that there isn't a methoxy group in the product above.
Instead, it kind of has two conjoined phosphate groups, which share the same oxygen. Another term for that is pyrophosphate
You could call it two separate phosphoryl groups. But that would be lacking some context; because the two phosphoryl groups are joined together by an oxygen.
Yup. Personally, I prefer that description, because in adenosine itself that oxygen is already present. So it's more like adenosine + phosphoryl + phosphoryl + phosphoryl...
ah, what would it look like with the bit not clipped off?
Also by the way, I heard that while ATP is called adenosine triphosphate. According to the rules, it should be something like adenosyl triphosphate. Do you agree with that?
@barlop Hmm... I think that's a different issue. Sometimes it's more a matter of history / convention, rather than an actual name that literally describes the compound. But yeah, if we were to go by literal naming, adenosyl triphosphate would be good.
In this case, though, I suspect that the naming "adenosine triphosphate" may have come from the fact that it can be formed by a condensation reaction between adenosine and a triphosphate group. I'll draw it out again:
So ATP = adenosine + triphosphate - H - OH (i.e. minus water).
So, it might arguably be a bit of a misnomer, but well... it's stuck.
Is there a general term that covers regardless of whether something is a phosphate group or a phosphoryl group. Like, phosph__ thing. Like, phosphus compound maybe?
Maybe "phosphate ester" might work. That refers to any molecule of the form R–O–phosphoryl.
(or equivalently, R–phosphate).
But that refers to the entire molecule, not just part of it. So whether that term is usable would kind of depend on the context you're using it in.
I think if I had to refer to either of the groups, I'd just literally write "phosphate/phosphoryl group". It's not particularly elegant, but it's clear.
@orthocresol Could you look at ATP as adenosine minus OH with triphosphate minus H. ? In which case, ATP could be seen legitimately as having the phosphate groups and that not being a misnomer. So the oxygen could legitimately be seen as part of the phosphor compounds.. Whether the oxygen came off the adenosine or off the triphosphate when they reacted, is perhaps arbitrary?
I recently took a Gen. Chem. 2 exam that contained this question. I answered false, as I knew that thermodynamics and kinetics are separate matters. My professor said the answer is true. I pressed him on it, citing a specific portion of our textbook that stated that the spontaneity of a reaction ...
@barlop If you mean us counting the atoms on paper, then yeah, it is quite arbitrary whether we take the OH away from adenosine or the triphosphate. But in the biosynthesis of ATP, I'm willing to bet that the oxygen comes from adenosine, i.e. it's (adenosine - H) + (triphosphate - OH).
I recently took a Gen. Chem. 2 exam that contained this question. I answered false, but my professor said the answer is true. My reasoning was that any electrons that leave the anode end up at the cathode, so the number of electrons should be conserved. This was consistent with the way we studied...
