144 Part II: Water, Enzymology, Biotechnology, and Protein Cross-linking
Table 6.2.General Rules for Generating Systematic Names and Guidelines for Common
Namesa
Rules and
Guidelines No. Descriptions
- Common names:Generally accepted trivial names of substances may be used in enzyme
names. The prefix D- should be omitted for all D-sugars and L- for individual amino
acids, unless ambiguity would be caused. In general, it is not necessary to indicate
positions of substitutes in common names, unless it is necessary to prevent two differ-
ent enzymes having the same name. The prefix keto-is no longer used for derivatives
of sugars in which -CHOH- has been replaced by –CO–; they are named throughout
as dehydrosugars.
Systematic names:To produce usable systematic names, accepted names of substrates
forming part of the enzyme names should be used. Where no accepted and convenient
trivial names exist, the official IUPAC rules of nomenclature should be
applied to the substrate name. The 1, 2, 3 system of locating substitutes should be
used instead of the system, although group names such as -aspartyl-,
-glutamyl- and also -alanine-lactone are permissible; and should normally be
used for indicating configuration, as in -D-glucose. For nucleotide groups, adenlyl
(not adenyl), etc. should be the form used. The name oxo acids (not keto acids) may
be used as a class name, and for individual compounds in which –CH2– has been
replaced by –CO–, oxo should be used. - Where the substrate is normally in the form of an anion, its name should end in -ate
rather than -ic,e.g., lactate dehydrogenase, not “lactic acid dehydrogenase.” - Commonly used abbreviations for substrates, e.g., ATP, may be used in names of
enzymes, but the use of new abbreviations (not listed in recommendations of the
IUPAC-IUB Commission on Biochemical Nomenclature) should be discouraged.
Chemical formulae should not normally be used instead of names of substrates.
Abbreviations for names of enzymes, e.g., GDH, should not be used. - Names of substrates composed of two nouns, such as glucose phosphate, which are
normally written with a space, should be hyphenated when they form part of the
enzyme names, and thus become adjectives, e.g., glucose-6-phosphate dehydrogenase
(EC 1.1.1.49). This follows standard practice in phrases where two nouns qualify a
third; see for example, Handbook of Chemical Society Authors, 2nd ed., p. 14 (The
Chemical Society, London, 1961). - The use as enzyme names of descriptions such as condensing enzyme, acetate-activating
enzyme,and pH 5 enzymeshould be discontinued as soon as the catalyzed reaction is
known. The word activatingshould not be used in the sense of converting the sub-
strate into a substance that reacts further; all enzymes act by activating their sub-
strates, and the use of the word in this sense may lead to confusion. - Common names:If it can be avoided, a common name should not be based on a
substance that is not a true substrate, e.g., enzyme EC 4.2.1.17 (Enoyl-CoA hydratase)
should not be called “crotonase,” since it does not act on crotonate. - Common names:Where a name in common use gives some indication of the reaction
and is not incorrect or ambiguous, its continued use is recommended. In other cases, a
common name is based on the same principles as the systematic name (see below), but
with a minimum of detail, to produce a name short enough for convenient use. A few
names of proteolytic enzymes ending in -inare retained; all other enzyme names
should end in -ase.