The origin of MEROPS and its changes

The beginning of MEROPS

The MEROPS system for the classification of peptidase had its beginning in 1993 and gave rise to an Internet database in 1996. Previous classifications of peptidases had relied upon specificity differences and catalytic type, but had not made much use of structural similarities. Rawlings & Barrett (1993) used primary and tertiary structures to group sets of homologous peptidases into families and sets of related families into clans. The idea of using the terms 'family' and 'clan' for the groups of peptidases came from a television documentary on bee-eaters, and because of this we chose the generic name of the bee-eater as the name of the database. In Greek mythology, Merops was a Trojan seer who was father-in-law to Priam, the King of Troy. The name was applied by Linnaeus to the European Bee-eater (Merops apiaster) in 1758.


The Whitefronted Bee-eater (Merops bullockoides) is a common resident of the banks of the Zambezi River and its tributaries. It nests in colonies that are divided into families and clans each of which occupies a different part of the colony and has its own discrete area away from the colony where the members hunt for flying insects.

Photograph - Peter Ginn Birding Safaris (1 Koer Street, Denneoord George 6530 R.S.A. e-mail:

Many releases

There are about four full releases of MEROPS each year, but some parts of the database are updated much more frequently. During the period 2000 - 2002 a special edition of the database called MEROPS-PRO was produced. This contain features of particular interest to our commercial users. In total, the releases of the academic and commercial versions of MEROPS prior to the present one have been as follows:

Release Date Release Date
1.1.1 Oct-1996
1.2.1 Feb-1997
1.2.2 Jun-1997
2.0 14-Jan-1998
3.0 Apr-1998
3.0.1 25-Jun-1998
3.0.2 12-Aug-1998
3.0.3 9-Sep-1998
3.1 22-Dec-1998
3.2 1-Apr-1999
3.2.1 12-May-1999
3.3 23-Jul-1999
3.4 5-Nov-1999
4.0 27-Jan-2000
5.0 17-Apr-2000
5.1 22-Jun-2000
5.2 31-Aug-2000
1.00 4-Sep-2000
5.3 4-Dec-2000 1.10 6-Dec-2000
5.4 23-Mar-2001 1.20 23-Mar-2001
5.5 16-Jun-2001 1.30 16-Jun-2001
5.6 25-Oct-2001 1.40 25-Oct-2001
5.6.1 29-Oct-2001 1.41 29-Oct-2001
5.7 17-Dec-2001 1.50 17-Dec-2001
5.8 19-Mar-2002 1.60 19-Mar-2002
5.9 21-Jun-2002 1.70 21-Jun-2002
6.0 30-Aug-2002 1.80 30-Aug-2002
6.1 10-Jan-2003
6.2 24-Mar-2003
6.3 23-Jun-2003
6.4 16-Sep-2003
6.5 22-Dec-2003
6.6 29-Mar-2004
6.7 30-Jun-2004
6.8 20-Aug-2004
6.9 16-Dec-2004
7.0 4-Apr-2005
7.1 22-Jul-2005
7.2 14-Oct-2005
7.3 22-Dec-2005
7.4 17-Mar-2006
7.5 14-Jul-2006
7.6 23-Oct-2006
7.7 22-Jan-2007
7.8 23-Apr-2007
7.9 17-Sep-2007
8.0 08-Jan-2008
8.0A 14-Feb-2008
8.1 05-May-2008
8.2 04-August-2008
8.3 22-December-2008
8.3 22-December-2008
8.4 06-April-2009
8.5 24-August-2009
9.0 15-December-2009
9.1 28-January-2010
9.2 28-April-2010
9.3 07-September-2010
9.4 31-January-2011
9.5 01-July-2011
9.6 29-February-2012
9.7 1-August-2012
9.8 17-December-2012
9.9 23-August-2013
9.10 20-December-2013

Changed identifiers

We try to keep all MEROPS identifiers as stable as possible, but ours is a rapidly developing field of science and sometimes changes are unavoidable. Families may merge when linking sequences are found, or disappear if the proteins contained in the family are found not to be peptidases after all. Families that were of unknown catalytic type are renamed when the information about the catalytic mechanism becomes available. An identifier that has been used in the past is never re-used. A list of all the changes that have taken place can be found here.