Bioinformatics Centre, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021. India
A study of characteristic distances in relation to sequence distances in protein structures shows that the distance signatures follow a non-random pattern and is independant of the type of protein. A range of spatial distances is found to be associated with each of the sequence distances. For example, at a sequence distance of 10 the maximum contribution is from the distance range 10-20 A while at a sequence distance of 50 the maximum contribution is from the 20-30 A range. However there is not a linear increase or decreas in the contributions to the different ranges as the sequence distance increases. Over a short range of sequence distances, the sequence distance versus percentage contribution shows a similar pattern in the different distance ranges. The sequence distances from 278-286 show a characteristic pattern of sequence distance versus spatial distance implying a possible structural motif. This approach will provide a way to take into account long range correlations in structure modelling. Details of the study involving the selected set of non homologous, low R factor and high resolution structures will be presented.