Peptides (version 2.4.6)

instaIndex: Compute the instability index of a protein sequence

Description

This function calculates the instability index proposed by Guruprasad (1990). This index predicts the stability of a protein based on its amino acid composition, a protein whose instability index is smaller than 40 is predicted as stable, a value above 40 predicts that the protein may be unstable.

Usage

instaIndex(seq)

Value

The computed instability index for a given amino-acids sequence

Arguments

seq

An amino-acids sequence

References

Guruprasad K, Reddy BV, Pandit MW (1990). "Correlation between stability of a protein and its dipeptide composition: a novel approach for predicting in vivo stability of a protein from its primary sequence". Protein Eng. 4 (2): 155 - 61. doi:10.1093/protein/4.2.155

Examples

# COMPARED TO ExPASy INSTAINDEX
# http://web.expasy.org/protparam/
# SEQUENCE: QWGRRCCGWGPGRRYCVRWC
# The instability index (II) is computed to be 83.68

instaIndex(seq = "QWGRRCCGWGPGRRYCVRWC")
# [1] 83.68