The lysozyme of the starfish Asteriasrubens

On the basis of a partial N-terminal sequence, Jolle`s and Jolle`s [Jolle`s, J., & Jolle`s, P. (1975) Eur. J. Biochem. 54, 19–23] previously proposed that the lysozyme from the starfish Asterias rubens represents a new form of lysozyme, called type i (invertebrate) lysozyme. Indeed, it differed from both the types c (chicken) and g (goose) known in other animals, as well as from plant and phage lysozymes. Recently, several proteins belonging to the same family have been isolated from protostomes. Here we report the com- plete mature protein sequence and cDNA sequence of the lysozyme from Asterias. These sequences vindicate the previously proposed homology between the starfish, a deuterostome, and protostome lysozymes. In addition, we present a structural analysis that allows us to postulate upon the function of several conserved residues.