SCHRODER VENTURES INTERNATIONAL LIFE SCIENCES FUND II LP2

                                                                       Exhibit 2

         Pursuant to Rule 13d-1(f)(1) under the Securities Exchange Act of 1934,
the undersigned hereby agree that only one statement containing the information
required by Schedule 13D need be filed with respect to the ownership by each of
the undersigned of shares of stock of Essential Therapeutics, Inc.

         This Agreement may be executed in any number of counterparts, each of
which shall be deemed an original.

         Executed this 29/th/ day of April, 2003.

                                        XXXXXXXX VENTURE MANAGERS LIMITED

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Directors


                                        XXXXXXXX VENTURES INTERNATIONAL LIFE
                                        SCIENCES FUND II LP1

                                        By: Xxxxxxxx Venture Managers Inc.,
                                            as General Partner

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Director and Vice President


                                        XXXXXXXX VENTURES INTERNATIONAL LIFE
                                        SCIENCES FUND II LP2

                                        By: Xxxxxxxx Venture Managers Inc.,
                                            as General Partner

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Director and Vice President


                                        XXXXXXXX VENTURES INTERNATIONAL LIFE
                                        SCIENCES FUND II LP3

                                        By: Xxxxxxxx Venture Managers Inc.,
                                            as General Partner

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Director and Vice President

                                        XXXXXXXX VENTURES INTERNATIONAL LIFE
                                        SCIENCES FUND II STRATEGIC PARTNERS L.P.

                                        By: Xxxxxxxx Venture Managers Inc.,
                                            as General Partner

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Director and Vice President


                                        XXXXXXXX VENTURES INTERNATIONAL LIFE
                                        SCIENCES FUND I GROUP CO-INVESTMENT
                                        SCHEME

                                        By: /s/ Xxxxx Xxxxxxx /s/ Xxxx Xxxx
                                           -------------------------------------
                                        Title: Directors



                                /s/ Xxxxx Xxxxxxx
                                ------------------------------------------------
                                Xxxxx Xxxxxxx, in his capacity as director of
                                Xxxxxxxx Venture Managers Limited

                                /s/ Xxxxxxx Xxxxxxx
                                ------------------------------------------------
                                Xxxxxxx Xxxxxxx, in her capacity as director of
                                Xxxxxxxx Venture Managers Limited

                                /s/ Xxxxxx Xxxxxx
                                ------------------------------------------------
                                Xxxxxx Xxxxxx, in her capacity as director of
                                Xxxxxxxx Venture Managers Limited

                                /s/ Xxxx Xxxx
                                ------------------------------------------------
                                Xxxx Xxxx, in his capacity as director of
                                Xxxxxxxx Venture Managers Limited