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PEPSTATS application details page
Protein statistics
pepstats outputs a report of simple protein sequence information including: - molecular weight
- number of residues
- average residue weight
- charge
- isoelectric point
- for each type of amino acid: number, molar percent, DayhoffStat
- for each physico-chemical class of amino acid: number, molar percent
- probability of protein expression in E. coli inclusion bodies
DayhoffStat is the amino acid's Dayhoff statistic divided by the molarpercent. The Dayhoff statistic is the amino acid's relative occurenceper 1000 aa normalised to 100 by rls@ebi.ac.uk (original work from 1993) The probability of expression in inclusion bodies is sometimesreferred to as a type of solubility measure. If, however, arecombinant protein is expressed in Escherichia coli, it can beexpressed as soluble in the cytosol or insoluble in inclusion bodies. Ifthe Harrison model predicts a given protein to be probably expressedin includion bodies, this doesn't mean that it is not possible to getit soluble in the cytosol. One example: Thermatoga maritima celldivison protein FtsA with a C-terminal His-Tag has a 58% Harrisonprobability of being expressed in inclusion bodies. However, there wasplenty of soluble protein in the E. coli cytosol (F. van den Ent andJ. Lowe, EMBO J. 19, 5300-5307 2000). If the protein is expressed ininclusion bodies or not is not only dependent on the sequence, butalso on many other factors, such as E. coli strain, incubationtemperature, type of expression vector, strength of promoter andmedium.
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