Protein structure
From DrugPedia: A Wikipedia for Drug discovery
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A number of residues are necessary to perform a particular [[biochemistry|biochemical]] function, and around 40-50 residues appears to be the lower limit for a functional [[protein domain|domain]] size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues.{{Fact|date=February 2008}} Very large aggregates can be formed from [[protein subunit]]s, for example many thousand [[actin]] molecules assemble into a collagen filament. | A number of residues are necessary to perform a particular [[biochemistry|biochemical]] function, and around 40-50 residues appears to be the lower limit for a functional [[protein domain|domain]] size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues.{{Fact|date=February 2008}} Very large aggregates can be formed from [[protein subunit]]s, for example many thousand [[actin]] molecules assemble into a collagen filament. | ||
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| + | ==Levels of protein structure== | ||
| + | [[Image:Protein-structure.png|thumb|250px|'''Protein structure''', from primary to quaternary structure.]] | ||
| + | Biochemistry refers to four distinct aspects of a protein's structure: | ||
| + | * '''Primary structure''' - the amino acid sequence of the peptide chains. | ||
| + | * '''Secondary structure''' - highly regular sub-structures (''[[alpha helix]]'' and ''strands of [[beta sheet]]'') which are locally defined, meaning that there can be many different secondary motifs present in one single protein molecule. | ||
| + | * '''Tertiary structure''' - three-dimensional structure of a single protein molecule; a spatial arrangement of the secondary structures. It also describes the completely folded and compacted polypeptide chain. | ||
| + | * '''Quaternary structure''' - complex of several protein molecules or polypeptide chains, usually called protein subunits in this context, which function as part of the larger assembly or protein complex. | ||
Revision as of 08:32, 18 August 2008
A number of residues are necessary to perform a particular biochemical function, and around 40-50 residues appears to be the lower limit for a functional domain size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues.Very large aggregates can be formed from protein subunits, for example many thousand actin molecules assemble into a collagen filament.
A number of residues are necessary to perform a particular biochemical function, and around 40-50 residues appears to be the lower limit for a functional domain size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues.Template:Fact Very large aggregates can be formed from protein subunits, for example many thousand actin molecules assemble into a collagen filament.
Levels of protein structure
Biochemistry refers to four distinct aspects of a protein's structure:
- Primary structure - the amino acid sequence of the peptide chains.
- Secondary structure - highly regular sub-structures (alpha helix and strands of beta sheet) which are locally defined, meaning that there can be many different secondary motifs present in one single protein molecule.
- Tertiary structure - three-dimensional structure of a single protein molecule; a spatial arrangement of the secondary structures. It also describes the completely folded and compacted polypeptide chain.
- Quaternary structure - complex of several protein molecules or polypeptide chains, usually called protein subunits in this context, which function as part of the larger assembly or protein complex.
