MoO-14

THE UPERINS - A NEW CLASS OF BIO-ACTIVE PEPTIDES. MS STRUCTURE, DETERMINATION.

Adrian M. Bradford, Mark J. Raftery,a John H. Bowie,a
John C. Wallace,b Michael J. Tylerc and Gregory W. Adamsd.

Departments of Chemistry,a Biochemistry,b and Zoology,c The University of Adelaide, South Australia, 5005.
dSchool of Pharmacy, University of California, San Francisco, CA 94143-0446. USA

The secretion of the granular dorsal glands of the floodplain toadlet Uperoleia inundata may be released by the benign method of electrical stimulation. The secretion contains more than fifty peptides as indicated by HPLC separation and FAB MS and MALDI TOF MS. The amino acid sequences of the twelve major peptides have been determined by FAB MS and allied methods. Examples of the structure determination will be detailed.

1. PEADPNAFYGLM(NH2)

2. GIVDFAKKVVGGIRNALGI(OH)

3. GVLDAFRKIATVVKNVV(NH2)

4. GLAGAISSALDKLKQSQLIKNWAKKLGYPR(NH2)

The majority of the peptides, called uperins, are host defence chemicals.

Uperin I (1) is a powerful neuropeptide related to the tachykinins and substance P. The majority of the peptides belong to the uperin 2 (2) and uperin 3 (3) families. These show antibiotic activity, and together constitute an effective 'antibiotic cocktail'. The Largest peptides belong to the uperin 6 family [e.g. uperin 6.1 (4)]: their function in the amphibian integument is not, as yet, understood.