Journal of Genetics

, Volume 73, Issue 1, pp 43–54

Studies on molecular evolution and structural features of double-headed inhibitors of α-amylase and trypsin in plants

  • Sameer Velankar
  • M. R. N. Murthy
Article

DOI: 10.1007/BF02927932

Cite this article as:
Velankar, S. & Murthy, M.R.N. J. Genet. (1994) 73: 43. doi:10.1007/BF02927932

Abstract

Plant seeds usually have high concentrations of proteinase and amylase inhibitors. These inhibitors exhibit a wide range of specificity, stability and oligomeric structure. In this communication, we report analysis of sequences that show statistically significant similarity to the double-headed α-amylase/trypsin inhibitor of ragi (Eleusine coracana). Our aim is to understand their evolutionary and structural features. The 14 sequences of this family that are available in the SWISSPROT database form three evolutionarily distinct branches. The branches relate to enzyme specificities and also probably to the oligomeric state of the proteins and not to the botanical class of the plant from which the enzymes are derived. This suggests that the enzyme specificities of the inhibitors evolved before the divergence of commercially cultivated cereals. The inhibitor sequences have three regions that display periodicity in hydrophobicity. It is likely that this feature reflects extended secondary structure in these segments. One of the most variable regions of the polypeptide corresponds to a loop, which is most probably exposed in the native structure of the inhibitors and is responsible for the inhibitory property.

Keywords

Inhibitorssequence comparisonevolutiontrypsinamylase

Copyright information

© Indian Academy of Sciences 1994

Authors and Affiliations

  • Sameer Velankar
    • 1
  • M. R. N. Murthy
    • 1
  1. 1.Molecular Biophysics UnitIndian Institute of ScienceBangaloreIndia