Polymerase chain reaction (PCR) amplification of mRNA from developing
barley (cultivar Haruna two-rows) endosperm was used to clone and sequ
ence full-length cDNA encoding beta-amylase. The beta-amylase cDNA was
1,775 bp in length. The beta-amylase was deduced to be composed of 53
5 amino acid residues and its molecular weight was calculated to be 59
,610. Kreis et al. reported that the beta-amylase cDNA from barley (cu
ltivar Hiproly) was 1,754 bp in length and coded for a polypeptide of
535 amino acids [Eur. J. Biochem. (1987) 169, 517-525]. A comparison o
f the beta-amylase sequences from Haruna two-rows and Hiproly barleys
revealed nine differences in the nucleotide sequence which resulted in
three changes in the amino acid residues and 21 additional nucleotide
s at its 3'-end in the cultivar Haruna two-rows. The three changes wer
e as follows: Ala-233, Ser-347, Met-527 (Haruna two-rows) and Val-233,
Met-347, Ile-527 (Hiproly). Lundgard and Svensson pointed out that 23
amino acid residues of the peptide fragment derived from the COOH-ter
minal region of barley (cultivar Gula) beta-amylase were in agreement
with the deduced amino acid sequence reported by Kreis et al., with th
e exception of a single position (Met-527 compared to Ile) [ Carlsberg
Res. Commun. (1986) 51, 487-491]. Our findings described above showed
Met-527 is reasonable. In the cases of beta-amylases from soybean and
sweet potato, the positions that corresponded to those at 233 and 347
in the amino acid sequence of beta-amylase from barley were Ala and S
er, respectively. Therefore, Ala-233 and Ser-347 in the amino acid seq
uence of barley beta-amylase were thought to be reasonable. Sequence h
omology of barley beta-amylase with the enzymes from soybean and sweet
potato amounted to 66.7 and 59.2%, respectively.