In view of the widespread use in biochemistry of labelling with hydrogen isotopes, recent IUPAC recommendations  for unambiguous naming of these isotopes may interest biochernists. There is often little harm in current practice of using the name 'proton' both for 1H+ and for H+ in its natural abundance of isotopes, but there are contexts in discussing isotope effects where distinction is necessary. The names listed in Table 1 allow the ambiguities to be avoided. Thus the general terms allow description of experiments on reaction mechanism, e.g. where hydronation is specifically with 2H+ or with 3H+, where the term 'protonation' would be misleading. The use of the recommendations may be illustrated by the following example: 'The observation of a protium/deuterium kinetic isotope effect may be interpreted in terms of the extent of hydron transfer in the transition state'.
Table 1. Names for hydrogen species
|Transfer of cation to substrate||hydronation||protonation||deuteronation||tritonation|
|Replacement of hydrogen by a specific isotope||protiation||deuteriation|
2. IUPAC Corninission on Physical Organic Chemistry (CPOC) Narnes for hydrogen atoms, ions, and groups, and for reactions involving them, Pure Appl. Chem. 1988, 60, 1115-1116.