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

Velankar, Sameer and Murthy, MRN (1994) Studies on molecular evolution and structural features of double-headed inhibitors of ?-amylase and trypsin in plants. In: Journal of Genetics, 73 (1). pp. 43-54.

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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 alpha-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.

Item Type: Journal Article
Publication: Journal of Genetics
Publisher: Indian academy of sciences
Additional Information: Copyright of this article belongs to Indian academy of sciences.
Keywords: lnhibitors;sequence comparison;evolution;trypsin;amylasel
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 13 Apr 2011 06:36
Last Modified: 13 Apr 2011 06:36
URI: http://eprints.iisc.ac.in/id/eprint/36842

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