Abstract: The present invention relates to the improved production of proteins, preferably enzymes such as lipases. In particular, the invention relates to a mutated signal peptide and nucleotide sequence encoding said signal peptide that results in an increased protein secretion. Further, the invention relates to a mutated promoter that results in an increased protein expression. It was surprisingly found that the combination of the mutated signal peptide and the mutated promoter act synergistically to result in an about 100-fold increased protein production. Nucleic acid molecules, expression vectors and host cells comprising the mutated signal peptide, mutated promoter, or the combination thereof are also encompassed by the invention. Finally, the invention relates to methods and uses of such nucleic acid molecules, expression vectors and host cells for protein preparation.