NOTICE OF ALLOWANCE OF TMT1 PATENT IN CANADA

8th May 2007

Proteome Sciences plc (“Proteome Sciences”) is pleased to announce that it has received the Notice of Allowance for Canadian Patent Application No. 2,403,114 entitled “Mass Markers” dated 13th April, 2007 (“TMT1”). TMT1 is the first patent filed describing isobaric mass tags and is part of a series of patents including TMT2 in Canada that was granted on 21st November, 2006. TMT1 has established a broad set of claims controlling the field of isobaric tandem mass tagging (Tandem Mass Tags® and TMT®) whilst TMT2 relates to more specific isobaric mass tag structures and various methods of use. The two patents are highly complementary, but TMT1, with its early priority and broader claims, is of greater significance.

The TMT1 Notice of Allowance is very important for Proteome Sciences because it will enable the company for the first time to approach entities using isobaric mass labels in Canada and to alert them that they can obtain licences from Proteome Sciences for the manufacture or use of any type of isobaric mass tags in their research programmes. Such licenses will allow revenue to be generated from any applications in the field of isobaric mass tagging.

Commenting on the Notice of Allowance Christopher Pearce, Chief Executive of Proteome Sciences said:

We are delighted that our first full set of patents covering isobaric tandem mass tagging (TMT®) have been allowed in Canada. This should be followed up shortly with similar allowances in Europe and the USA.

In Europe, the patent process for TMT1 is nearly completed with the Rule 51(4) Notice of Intention to Grant having been published and the patent expected to be issued in the near future. In the USA, the TMT1 and TMT2 patent applications are in the final stages of processing and we anticipate that these too will be concluded shortly.

Having acquired the TMT® technology in 2002, Proteome Sciences was provided with both the earliest date of invention of isobaric mass tagging and the patents for the technology. Our goal is to have a full range of TMT® products launched in the market in the second half of the year. These have been developed in-house over the last year and, with the issuance of the patents and the completion of the licensing processes, we will be in the position to generate substantial revenues from a combination of licence payments, back-licence payments, product sales and royalties. The market for isobaric tandem mass tags continues to grow disproportionately fast and earlier estimates over the patent lives appear to have considerably underestimated the scale and importance of quantitative mass spectrometry.

After the delays, we intend to make the most of the value of TMT® for our shareholders.