SHE, a Starch Hydrolytic Enzyme active in maize endosperm (Zea mays), and the cDNA sequence encoding SHE are disclosed. The specificity of native, purified SHE is similar, in general terms, to previously known alpha-amylases. However, the activity of SHE toward amylopectin results in hydrolysis products that are distinctly different from those of other alpha-amylases. SHE, and its homologous equivalents in other plants such as rice, Arabidopsis, apple and potato, can be used in starch processing for generating different, e.g., larger sized, alpha-limit dextrins for industrial use, as compared to those generated by previously known alpha-amylases or other starch hydrolytic enzymes. In addition, modification of the expression of this enzyme in transgenic maize plants or in other transgenic organisms (including bacteria, yeast, and other plant species) can be useful for the generation of novel starch forms or altered starch metabolism.