Biochemistry in Tables, Schemes, and Graphs - S.D. Zhamsaranova 2009
Structure and Characteristics of Proteinogenic Amino Acids
Protein Structure
Peptide chains contain dozens, hundreds, and thousands of amino acid residues linked by strong peptide bonds. Through intramolecular interactions, Proteins form a specific spatial architecture known as protein conformation. There are four Levels of Protein structural Organization.
Primary Structure is the linear sequence of amino acid residues within a polypeptide chain.
Secondary Cell/13.html">Protein Structure is the spatial conformation formed As a result of interactions between the Functional groups of the peptide backbone. The polypeptide chain can thus adopt two primary structural types: a-helices and ß-structures.
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Tertiary Protein Structure is the three-dimensional spatial conformation formed through interactions between amino acid side chains that may be located at considerable distances from one another along the peptide chain.
BONDS STABILIZING THE Tertiary Structure of A GLOBULAR PROTEIN
Only selected pairs of interacting side chains are shown
TYPES OF AMINO ACID SIDE CHAINS AND THE BONDS THEY FORM
Types of side chains |
Corresponding |
Approximate content in proteins |
Bonds formed by side chains |
Nonpolar side chains |
Gly, Ala, Val, Leu, Ile, Phe, Trp, Pro |
50% |
“Hydrophobic” and Van der Waals (induction and dispersion) interactions |
Polar un-ionizable side chains |
Ser, Thr, Cys, Tyr, Asn, Gln |
20% |
Hydrogen Bonds; Disulfide Bonds as well for Cys |
Polar side chains ionizable at physiological pH |
Asp, Glu, Arg, Lys, His |
30% |
Ionic and hydrogen bonds |
TERTIARY STRUCTURE OF Insulin
Coils represent a-helical regions, and cylindrical curves indicate non-regular regions. Dashed lines denote hydrogen bonds, while solid lines indicate S-S bridges.
SELECTED Conjugated Proteins
Proteins |
Prosthetic group |
Н3РО4 |
|
Heme groups |
|
Ribonucleoproteins (Ribosomes, etc.) |
RNA |
Deoxyribonucleoproteins (Chromatin) |
DNA |
QUATERNARY Spatial Structure of HUMAN Hemoglobin
Hemoglobin is an oligomeric protein. Its primary function is The transport of O2 from the Lungs to Tissues. This function is regulated by various ligands.
It consists of four subunits: two a chains (141 amino acid residues each) and two ß chains (146 residues each). The ß-subunits are highlighted in a darker shade. Each subunit is bound to a single heme molecule, shown in black.
Protein Denaturation and THE MAINTENANCE OF NATIVE CONFORMATION IN THE CELLULAR ENVIRONMENT
Protein denaturation is the disruption of a protein's native conformation caused by the Cleavage of weak bonds that stabilize its spatial structures under the action of Denaturing Agents.
Reagents AND CONDITIONS CAUSING PROTEIN DENATURATION
Denaturing agents |
|
High Temperature (above 600 С) |
Disruption of weak bonds within the protein |
Acids and alkalis |
Alteration of ionizable group ionization, cleavage of ionic and hydrogen bonds |
Urea |
Disruption of intramolecular hydrogen bonds through The formation of hydrogen bonds with urea |
Alcohol, phenol, chloramine |
Disruption of hydrophobic and hydrogen bonds |
Heavy metal salts |
Formation of insoluble protein-heavy metal salts |
Last update: 06/08/2026
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