Abstract: A DNA cassette for expression and secretion of a given amino acid, polypeptide or protein in a host strain of corynebacterium, including a sequence which encodes the amino acid, polypeptide or protein, and a region of chromosomal or plasmid DNA, wherein the sequence is situated in the region of chromosomal or plasmid DNA such that the sequence is transcribed with, at the sequence's 5' end, at least one portion of a sequence encoding the signal sequence of the protein PS1 or PS2, the at least one portion ensuring the secretion of the amino acid, polypeptide or protein after translation when the DNA cassette is incorporated into the host strain of corynebacterium.

Abstract: A polymeric enzyme having a molecular weight higher than or equal to 200,000 and not exhibiting any proteolytic activity on casein derived from a culture of Micrococcus caseolyticus is disclosed, as is a method of producing the enzyme by filtration on gel buffered with an aqueous buffer of an enzymatic system prepared by lyophilization of an aqueous concentrate formed by ultrafiltration of the solution obtained by dissolving, in an aqueous solution of calcium chloride, an enzymatic system precipitated from a supernatant of a micro-organism culture broth by ammonium sulphate, wherein the enzyme is not retained on a gel calibrated for proteins with a molecular weight of between 5,000 and 20,000, buffered with a 20 mM TRIS-HCl buffer, at pH 7.5, containing 1.5 mM calcium chloride, and the enzymatic system is derived from a culture broth of said Micrococcus caseolyticus. The enzyme may be used for the production of aspartame by condensation of L-aspartic acid with methyl DL-phenylalaninate.