Karplus equation
E467018
conformational analysis method
empirical equation
relationship in nuclear magnetic resonance spectroscopy
The Karplus equation is an empirical relationship in nuclear magnetic resonance (NMR) spectroscopy that correlates three-bond scalar coupling constants with dihedral angles, enabling the determination of molecular conformations.
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
conformational analysis method
ⓘ
empirical equation ⓘ relationship in nuclear magnetic resonance spectroscopy ⓘ |
| appliesTo |
3J scalar coupling constants
ⓘ
three-bond heteronuclear coupling constants ⓘ vicinal proton–proton coupling constants ⓘ |
| assumes |
fixed average geometry for a given coupling pathway
ⓘ
smooth periodic dependence of coupling on dihedral angle ⓘ |
| basedOn | empirical fit to experimental NMR data ⓘ |
| correlates |
dihedral angles
ⓘ
three-bond scalar coupling constants ⓘ |
| developedBy | Martin Karplus NERFINISHED ⓘ |
| field |
nuclear magnetic resonance spectroscopy
ⓘ
organic chemistry ⓘ physical chemistry ⓘ structural biology ⓘ |
| hasExtension |
generalized Karplus equations
ⓘ
stereospecific Karplus relationships NERFINISHED ⓘ |
| hasGeneralForm | 3J = A cos²(θ) + B cos(θ) + C ⓘ |
| hasLimitation |
accuracy decreases for highly flexible systems
ⓘ
parameters are system-dependent ⓘ sensitive to averaging over multiple conformations ⓘ |
| hasMaximumCouplingNear |
0 degrees dihedral angle
ⓘ
180 degrees dihedral angle ⓘ |
| hasMinimumCouplingNear | 90 degrees dihedral angle ⓘ |
| hasParameter |
A
ⓘ
B ⓘ C ⓘ |
| hasPeriodicity | 360 degrees in dihedral angle ⓘ |
| hasVariable |
3J coupling constant
ⓘ
dihedral angle θ ⓘ |
| inspired | Karplus-type relationships for other couplings ⓘ |
| namedAfter | Martin Karplus NERFINISHED ⓘ |
| parameterDependsOn |
bond geometry
ⓘ
substituents and electronic environment ⓘ type of nuclei involved ⓘ |
| publicationDecade | 1950s ⓘ |
| relatedTo |
J-coupling
ⓘ
NMR structure determination ⓘ conformational analysis ⓘ dihedral angle ⓘ |
| usedFor |
conformational analysis of organic molecules
ⓘ
conformational analysis of peptides and proteins ⓘ determination of molecular conformations ⓘ estimation of dihedral angles from NMR data ⓘ |
| usedIn |
carbohydrate conformational analysis
ⓘ
protein structure determination ⓘ small-molecule structure elucidation ⓘ solution-state NMR spectroscopy ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.