Conserved amino acid sequence domains in alpha-amylases from plants, mammals, and bacteria.

Although alpha-amylases from mammals, plants, and bacteria have common functions, the amino acid sequences of enzymes from these three, evolutionarily distant groups of organisms are not known to share common homologies, and active sites have not been identified. Here I demonstrate that there are three sequence domains common to all alpha-amylases that are aligned and spaced at similar intervals along the length of each protein. The first domain in the barley enzymes appears to contain a calcium binding site. These common domains may represent important functional regions, perhaps the active sites.