THE ORIGIN OF TRYPSIN - EVIDENCE FOR MULTIPLE GENE DUPLICATIONS IN TRYPSINS

The trypsin family of serine proteases is one of the most studied prot ein families, with a wealth of amino acid sequence information availab le in public databases. Since trypsin-like enzymes are widely distribu ted in living organisms in nature, likely evolutionary scenarios have been proposed. A novel methodology for Fourier transformation of biolo gical sequences (FOTOBIS) is presented. The methodology is well suited for the identification of the size and extent of short repeats in pro tein sequences. In the present paper the trypsin family of enzymes is analyzed with FOTOBIS and strong evidence for tandem gene duplication is found. A likely evolutionary path for the development of present-da y trypsins involved an intrinsic extensive tandem gene duplication of a small DNA fragment of 15-18 nucleotides, corresponding to five or si x amino acids. This ancestral trypsin gene was subsequently duplicated , leading to the earliest version of a full-sized trypsin, from which the contemporary trypsins have developed.