a-Amylases catalyze the hydrolysis of a-1,4 glucan linkages in
starch and are widely distributed in nature, being found in bacteria,
plants and animals. In humans, a-amylase is composed
of 496 amino acids in a single polypeptide chain, which is encoded
on chromosome 1 as part of a multigene family (Gumucio
et al., 1988). These genes are regulated so that different isozymes
are synthesized in either salivary glands or the pancreas. The salivary
and pancreatic a-amylases are highly homologous in terms
of primary sequence (Nishide et al., 1986) but do exhibit somewhat
different cleavage patterns (Minamiura, 1988). The functional
differences observed undoubtedly arise from the 15 amino