Protein Structure Levels

This section provides a quick introduction of protein structure levels, Primary, Secondary, Tertiary and Quaternary structure levels.

What Are Protein Structure Levels? - A large protein conformation can be considered to have 4 structure levels from a construction point of view.

1. Primary Structure Level The primary structure of proteins is the protein sequence of its amino acid residues linked by peptide bonds. The primary structure of a protein is represented by a sequence of abbreviations of its linked amino acid residues. For example, the Trp-Cage protein has the following primary structure.

NLYIQWLKDGGPSSGRPPPS

2. Secondary Structure Level The secondary structure is the ordered arrangement of amino acid residues in localized regions of a protein. The two main secondary structures are the alpha helix and beta sheet. Hydrogen bondings are used to stabilize these arrangements. See next section for more details.

3. Tertiary Structure Level The tertiary structure of a protein is the three-dimensional arrangement of secondary structures of a protein. A tertiary structure is largely maintained by disulfide bonds. which are formed between the side chains of cysteine by oxidation of two thiol groups (SH) to form a disulfide bond (S-S), also sometimes called a disulfide bridge.

4. Quaternary Structure Level The quaternary structure is used to describe composed proteins (or protein complexes), which consists of multiple noncovalently-linked protein sequences. A quaternarytiary structure is mainly stabilized by hydrophobic interactions.

Table of Contents

 About This Book

 Introduction of Molecules

 Molecule Names and Identifications

 Molecule Mass and Weight

Protein and Amino Acid

 What Is Amino Acid

 The 20 Common Amino Acids

 Peptide, Peptide Bond, Amino Acid Residues

 What Is Protein

Protein Structure Levels

 Alpha Helix and Beta Sheet

 Protein Visualization - Ribbon Diagram

 Composed Proteins or Protein Complexes

 wwpdb.org - Worldwide PDB (Protein Data Bank)

 What Is FASTA

 Nucleobase, Nucleoside, Nucleotide, DNA and RNA

 Gene and Chromosome

 Protein Kinase (PK)

 DNA Sequencing

 Gene Mutation

 SDF (Structure Data File)

 PyMol Installation

 PyMol GUI and CLI

 PyMol Selections

 PyMol Editing Functions

 PyMol Measurement Functions

 PyMol Movie Functions

 PyMol Python Integration

 PyMol Object Functions

 ChEMBL Database - European Molecular Biology Laboratory

 PubChem Database - National Library of Medicine

 PDB (Protein Data Bank)

 INSDC (International Nucleotide Sequence Database Collaboration)

 HGNC (HUGO Gene Nomenclature Committee)

 Relocated Tutorials

 Resources and Tools

 Molecule Related Terminologies

 References

 Full Version in PDF/EPUB