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Chemical Shift And its Use in Structure Determination. It has been know for a long while that: The chemical shift is dependant on the secondary structure, and Homologous proteins have homologous shifts. = W rc + W sec rc random coil shift sec secondary shift, Depends on
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Chemical Shift And its Use in Structure Determination • It has been know for a long while that: • The chemical shift is dependant on the secondary structure, and • Homologous proteins have homologous shifts
= Wrc + Wsec • rc random coil shift • sec secondary shift, Depends on conformation H-bond(s) Neighboring residue type etc
Available proteins Alpha-lytic protease BPTI Calbindin Calmodulin Calmodulin//M13 Cutinase Cyclophyllin Cyanivirin-N Dehydrase MBP HIV protease Human carbonic anhydrase Human thioredoxin red. Serine Protease PB92 Staph nuclease Ubiquitin III-glc Interleukin 1a Metallo-lactamase Profilin
Residue A R D N C Q E G H I L K M F P S T W Y V Residue A R D N C Q E G H I L K M F P S T W Y V A 0 1 1 1 1 1 1 2 1 2 1 1 1 2 3 1 2 2 2 2 R1 0 1 1 1 1 1 2 1 2 1 0 1 1 3 1 2 1 1 2 D1 1 0 0 1 1 1 2 1 2 1 1 1 1 3 1 2 1 1 2 N1 1 0 0 1 1 1 2 1 2 1 1 1 1 3 1 2 1 1 2 C1 1 1 1 0 1 1 2 1 2 1 1 1 1 3 1 2 1 1 2 Q1 1 1 1 1 0 1 2 1 2 1 1 1 1 3 1 2 1 1 2 E1 1 1 1 1 1 0 2 1 2 2 2 1 1 3 1 2 1 1 2 G2 2 2 2 2 2 2 0 3 3 3 3 3 3 3 3 3 3 3 3 H1 1 1 1 1 1 1 3 0 2 1 2 2 1 3 2 2 1 1 2 I2 2 2 2 2 2 2 3 2 0 1 2 2 2 3 2 1 2 2 0 L1 1 1 1 1 1 2 3 1 1 0 1 1 1 3 2 2 1 1 2 K1 0 1 1 1 1 2 3 2 2 1 0 1 2 3 1 2 2 2 2 M1 1 1 1 1 1 1 3 2 2 1 1 0 2 3 1 2 2 2 2 F2 1 1 1 1 1 1 3 1 2 1 2 2 0 3 2 2 0 0 1 P3 3 3 3 3 3 3 3 3 3 3 3 3 3 0 3 3 3 3 3 S1 1 1 1 1 1 1 3 2 2 2 1 1 2 3 0 1 2 2 2 T 2 2 2 2 2 2 2 3 2 1 2 2 2 2 3 1 0 1 1 1 W2 1 1 1 1 1 1 3 1 2 1 2 2 0 3 2 1 0 0 1 Y2 1 1 1 1 1 1 3 1 2 1 2 2 0 3 2 1 0 0 1 V2 2 2 2 2 2 2 3 2 0 2 2 2 1 3 2 1 1 1 0
Limitation: Size of the Database: 20.pbd files Solution: The Database can be ‘extrapolated’ By constructing Surfaces that describe the (f,y) Dependance of the Secondary Shift Shifts can be simulated for arbitrary .pdb files .pdb database can be mined for fragments of arbitrary length ‘Inverse Talos’
Problems: When Shifts do not depend on backbone conformation (Cofactors, Metal Centers, Hyperfine Shifts, H-bonds) Gly surfaces have two-fold symmetry (potential source of errors) No ‘long range information’ Only secondary structure information, Tertiary structure requires additional constraints NOE at the interfaces, RDC, etc … Can be combined with methods of Bioinformatics, Sequence alignment, Structure prediction,
CS homology CS homology model 1gb3.pdb