independent of chromosomal replication e g a plasmid a bacteriophage or an extrachromosomal element minichromosome or an artificial chromosome alternatively the vector may be one which when introduced into a host cell is integrated into the host cell genome and replicated together with the chromosome s into which it has been integrated in the vector the dna sequence should be operably connected to a suitable promoter sequence the promoter may be any dna sequence which shows transcriptional activity in the host cell of choice and may be derived from genes encoding proteins either homologous or heterologous to the host cell examples of suitable promoters for directing the transcription of the dna sequence encoding a maltogenic alpha amylase variant of the invention especially in a bacterial host are the promoter of the lac operon of e coli the streptomyces coelicolor agarase gene daga promoters the promoters of the bacillus licheniformis u03b1 amylase gene amyl the promoters of the bacillus stearothermophilus maltogenic amylase gene amym the promoters of the bacillus amyloliquefaciens u03b1 amylase amyq the promoters of the bacillus subtilis xyla and xylb genes etc for transcription in a fungal host examples of useful promoters are those derived from the gene encoding a oryzae taka amylase rhizomucor miehei aspartic proteinase a niger neutral u03b1 amylase a niger acid stable.