16-10-2010, 10:15 AM
Protein Secondary Structure Prediction
Proteins
Protein: from the Greek word PROTEUO which means "to be first (in rank or influence)"
Why are proteins important to us:
Proteins make up about 15% of the mass of the average person and maintain the structural integrity of the cell.
Enzyme – acts as a biological catalyst
Storage and transport – Haemoglobin
Antibodies
Hormones – Insulin
Introduction to proteins
These values can be calculated?
Ramachandran Plot: Founded by G.N.Ramachandran.
Green region indicates the
stericially permitted φ & Ψ values except Gly and Pro.
Yellow circles represent the conformational angles of several secondary structures..α-helix, parallel & anti parallel β-sheet
Secondary Structure
8 different categories (DSSP):
H: - helix
G: 310 – helix
I: - helix (extremely rare)
E: - strand
B: - bridge
T: - turn
S: bend
L: the rest
Three secondary structure states
Prediction methods are normally trained and assessed for only 3 states (residues):
H (helix), E (strands) and L (coil)
There are many published 8-to-3 states reduction methods
Standard reduction methods are defined by programs DSSP (Dictionary of SS of Proteins), STRIDE, and DEFINE
Improvement of predictive accuracy of different SSP (Secondary Structure Prediction) programs depends on the choice of the reduction method
For more information about this article,please follow the link:
http://www.googleurl?sa=t&source=web&cd=...insSSP.ppt&ei=tC25TK_zLYLJcbOT6a0M&usg=AFQjCNGAmvtStrD0iQHSKPfgeuycZSvlwA