Relationships, derived from optimum alignments, among amino acid sequences of plant peroxidases

Abstract

The amino acid and (or) DNA sequences of 13 plant peroxidases (EC 1.11.1.7), which include isozymes within species, are currently available in data bases; all have similar lengths of approximately 300 amino acids. Sequence relationships among these 13, plus 2 microbial peroxidases of similar length, were examined. The 15 sequences were compared in all 105 pairwise combinations using optimum alignment procedures. Gap penalties were determined from analysis of penalty change effects. Distances between sequences generated by optimum alignments were analysed by clustering techniques to generate dendrograms. Specific distances, which provided pairwise distance measurements independent of the average distance for a sequence, were used to evaluate sequence similarities; closely related sequences produce closely correlated specific distances. Among the seven plant species, five subgroups were established: (1) horseradish isoperoxidases, (2) turnip and wheat, (3) cucumber and tobacco, (4) potato and tomato, and (5) in which cytochrome c peroxidase showed some similarity to ligninase, but both were only distantly related to plant peroxidases. Horseradish isoperoxidases were related to sequences in subgroups 2, 3, and 4 but resembled subgroups 2 and 3 more closely than 4. Subgroup 2 was more related to 3 than any other. Key words: plant peroxidases, sequence relationships, peroxidase profiles.