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Why is deoxyadenosine monophosphate called "dAMP" and not "DAMP"?

After all, deoxyribonucleic acid is called "DNA", and not "dNA" (nor "dRNA", thanks for that insight, @Karsten Theis), and so it looks like "deoxy" or "deoxyribo" is "D" and not "d" in the case of DNA.

It seems that "dAMP" is generated using a different rule. I wonder why? "DAMP" has the advantage of being easily recalled, because it is an English word.

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    $\begingroup$ It would be dRNA, not dNA. $\endgroup$ Jan 28 at 11:22
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    $\begingroup$ @KarstenTheis mind blown $\endgroup$ Jan 28 at 11:49
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    $\begingroup$ There is also ddATP, dideoxy, used as chain terminator in DNA sequencing. $\endgroup$ Jan 28 at 14:16

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See this result from Biology: The Dynamic Science. Peter J. Russell, Paul E. Hertz, and Beverly McMillan, p.65-66 (2007):

The lowercase d in the abbreviation indicates that the nucleoside contains a deoxyribose form of the sugar.

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    $\begingroup$ +1 The Windows 10 screen magnifier was very useful for looking at the link, and with that I must say that it is a fabulous summary IMHO of the structure of DNA. What a pleasure. So much better than Wikipedia IMHO. It shows that my question is a fairly good and original one, I think. $\endgroup$ Jan 28 at 3:30
  • $\begingroup$ +1 Though I wrote a separate answer, I did wondered why was the lowercase chosen instead of uppercase. In fact, we have DNA but not dNA. $\endgroup$ Jan 28 at 11:51
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While the current answers say what d stands for, they don't really explain why D wasn't chosen instead. We could, for example, equally say that "D shows that it has deoxyribose..."

I offer this without any evidence (and without knowing whether such evidence exists). If you are interested in evidence, you will likely have to find the original article / work in which these were named, and hope that the author included some rationale.

AMP, adenosine monophosphate, is already an important biomolecule. Prefixing it with a lowercase d in dAMP suggests that it is the same as AMP, but just modified by a little bit (which is true; it just has one oxygen less). This is perhaps partly stylistic, but it also makes it easy to recognise visually as the small letter does not stand out as much. There are also other parallel examples, such as cyclic AMP (written as cAMP).

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    $\begingroup$ Sometimes the lowercase prefix designates isomers, iPrOH or tBuOH, sometimes function, mRNA or cDNA, and sometimes a different molecule, dTTP or cAMP. $\endgroup$ Jan 28 at 11:40
  • $\begingroup$ @KarstenTheis Indeed, that is a very wide range of examples! $\endgroup$
    – orthocresol
    Jan 28 at 11:41
  • $\begingroup$ +1 This was in fact my very first question as to why lowercase d is used rather than uppercase. Though this was considered as standard abbreviation, they didn't explain why did they choose the lowercase instead of uppercase. In fact, we have DNA but not dNA. $\endgroup$ Jan 28 at 11:46

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