Unit for catalytic activity coherent with the SI, equal to the catalytic activity
that catalyses a reaction rate of one
mole per second in an
assay system.

.
The
katal is recommended for use in the specific context of
enzymes and clinical chemistry.
Source:
PAC, 1996, 68, 957
(Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations
1996))
on page 977
See also:
PAC, 1994, 66, 2587
(Glossary of bioanalytical nomenclature - Part 1: General terminology, body fluids,
enzymology, immunology (IUPAC Recommendations 1994))
on page 2595