Relationship between enzyme heterozygosity and quaternary structure

The need for proteins to maintain particular quaternary structures constrains variability in amino acid sequence. Monomeric enzymes are then expected to be more variable than dimeric forms, which in turn are expected to be more variable than tetrameric forms. These predictions are confirmed by analysis of available data on enzyme variation. Theories relating enzyme heterozygosity to metabolic function are discussed in the light of these findings.Financial support for part of the work described in this article was derived from NERC Grant GR3/1558 to J. A. Beardmore.