Abstract
The three-dimensional structure of chicken triose phosphate isomerase consists of an eightfold repeat of a βα. unit. We have investigated whether there is evidence of (1) gene replication within TIMase † † Abbreviation used: TIMase, triose phosphate isomerase; LDHase, lactate dehydrogenase; ADHase, alcohol dehydrogenase; GPDHase, glyceraldehyde 3-phosphate dehydrogenase; NAD, nicotinamide adenine dinuclcotide. ; and (2) a common genetic origin for TIMase and dogfish lactate dehydrogenase, another protein with a ( βα) 2- β structure. Alpha carbon atoms of the βα. units and of the ( βα) 2- β units were superimposed to minimise the sum of the root-mean-square distances between equivalenced atoms. Four measures of similarities between amino acids wore used in comparison of the sequences. These methods gave no definitive evidence of gene replication within TIMase. In the comparison between TIMase and lactate dehydrogenase, some three-dimensional and sequence similarities were found which can be combined to suggest that some sections of the molecules are related. However, one cannot distinguish with any certainty between convergent and divergent evolution as explanations for the apparent relationship.
Published Version
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