This document discusses the concepts of configuration and conformers in biomolecules. It defines configuration as the permanent geometry of a molecule that can only change by breaking bonds, while conformation refers to the spatial arrangement of atoms in a molecule that can change without breaking bonds. The document outlines different concepts used to describe configuration, including cis-trans for double bonds, D-L and R-S systems for chiral carbons, and (+)-(-) enantiomers related to rotation of plane-polarized light. It also discusses the need to study biomolecular structure and provides examples of conformers in proteins and nucleic acids, ranging from primary to quaternary structure.

1. CONFIGURATION &
CONFORMERS OF
BIOMOLECULES
Presented By-
ANSHIKA BANSAL
BSc Hons
DEI, Agra
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2. CONTENTS-
 INTRODUCTION
 NEED TO STUDY
 DIFFERENT CONCEPTS-
 cis –trans concept
 Relative configuration erythros-threos concept
 D-L concept
 (+) & (-) enantiomeres
 Absolute configuration (R-S concept)
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3. INTRODUCTION
Configuration -
 Configuration is permanent geometry
 refers to spatial arrangement of bonds
 can be changed only by breaking bonds
 Example: L- & D and R- & S- configurations
CONFORMERS-
o Conformation is the spatial arrangement of atoms in a
molecule
o It can be changed without breaking bonds.
o Example- rotation about single bonds produce the cis-
trans, and E-Z conformations
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4. NEED TO STUDY
 To study the 3D structure of biomolecules
systematically
 To understand the physical and chemical nature of
biomolecules
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5. DIFFERENT CONCEPTS FOR
CONFIGURATION
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6. 1) CIS-TRANS CONCEPT
 Showed by double bond containing compounds
 Same side- cis
 Opposite side- trans
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7. EXAMPLES-
In amino acids chain In lipids
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8. 2) ERYTHROS-THREOS CONCEPT-WHEN 2
CHIRAL CARBON IS PRESENT
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9. EXAMPLE- IN CARBOHYDRATES
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10. 3) D-L CONCEPT= RELATIVE
CONFIFURATION
 L isomers have the hydroxy group attached to the
left side of the asymmetric carbon furthest from the
carbonyl
 while D isomers have the hydroxy group on the
right side.
 NOTE- Naturally occurring sugars are D
isomers.
Only L form of amino acids are found in proteins
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11. EXAMPLE-
In carbohydrates In amino acids
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12. 4) (+) AND (-) ENANTIOMERS
 (+) enantiomers rotate plane-polarized light
clockwise (also called dextrorotary, abbreviated d)
 while (-) enantiomers rotate it counter-clockwise
(levorotary, or l).
 Measured by polarimeter
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13. 5) R-S CONCEPT
RULES-
 Assign sequence priorities to the four substituents by
looking at the atoms attached directly to the chiral
center.
1. The higher the atomic number of the immediate substituent
atom, the higher the priority.
2. If two substituents have the same immediate substituent
atom, evaluate atoms progressively further away from the chiral
center until a difference is found.
3. If double or triple bonded groups are encountered as
substituents, they are treated as an equivalent set of single-
bonded atoms. 13

14. EXAMPLES
 R(rectus = right)
 S(sinister = left)
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15. CONFORMERS OF
BIOMOLECULES
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16. CONFORMERS OF PROTEINS
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17. PRIMARY STRUCTURE-
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18. SECONDARY STRUCTURES
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α-helix β-pleated

19. TERTIONARY STRUCTURE
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20. QUADANARY STRUCTURE
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21. CONFORMER OF NUCLEIC ACID
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23. THANK YOU
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