In
biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
, the native state of a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
or
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...
is its properly
folded and/or assembled form, which is operative and functional. The native state of a biomolecule may possess all four levels of
biomolecular structure
Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule of protein, DNA, or RNA, and that is important to its function. The structure of these molecules may be considered at any of several length s ...
, with the secondary through quaternary structure being formed from weak interactions along the covalently-bonded backbone. This is in contrast to the
denatured state, in which these weak interactions are disrupted, leading to the loss of these forms of structure and retaining only the biomolecule's primary structure.
Biochemistry
Proteins
While all protein molecules begin as simple unbranched chains of
amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
, once completed they assume highly specific three-dimensional shapes. That ultimate shape, known as
tertiary structure
Protein tertiary structure is the three dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains. Amino acid side chains may int ...
, is the folded shape that possesses a minimum of
free energy. It is a protein's tertiary, folded structure that makes it capable of performing its biological function. In fact, shape changes in proteins are the primary cause of several
neurodegenerative disease
A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic ...
s, including those caused by
prion
Prions are misfolded proteins that have the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many other animals. It ...
s and
amyloid
Amyloids are aggregates of proteins characterised by a Fibril, fibrillar morphology of 7–13 Nanometer, nm in diameter, a beta sheet (β-sheet) Secondary structure of proteins, secondary structure (known as cross-β) and ability to be Staining, ...
(i.e.
mad cow disease
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is an incurable and invariably fatal neurodegenerative disease of cattle. Symptoms include abnormal behavior, trouble walking, and weight loss. Later in the course of t ...
,
kuru
Kuru may refer to:
Anthropology and history
* Kuru (disease), a type of transmissible spongiform encephalopathy associated with the cannibalistic funeral practices of the Fore people
* Kuru (mythology), part of Meithei mythology
* Kuru Kingdom, ...
,
Creutzfeldt–Jakob disease
Creutzfeldt–Jakob disease (CJD), also known as subacute spongiform encephalopathy or neurocognitive disorder due to prion disease, is an invariably fatal degenerative brain disorder. Early symptoms include memory problems, behavioral changes, ...
).
Many
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s and other non-structural
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
s have more than one native state, and they operate or undergo regulation by transitioning between these states. However, "native state" is used almost exclusively in the singular, typically to distinguish properly
folded proteins from
denatured or unfolded ones. In other contexts, the folded shape of a protein is most often referred to as its native "
conformation" or "structure."
Folded and unfolded proteins are often easily distinguished by virtue of their water solubilities, as many proteins become insoluble on denaturation. Proteins in the native state will have defined
secondary structure
Protein secondary structure is the three dimensional conformational isomerism, form of ''local segments'' of proteins. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta ...
, which can be detected spectroscopically, by
circular dichroism and by
nuclear magnetic resonance
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...
(NMR).
The native state of a protein can be distinguished from a
molten globule
In molecular biology, the term molten globule (MG) refers to protein states that are more or less compact (hence the "globule"), but are lacking the specific tight packing of amino acid residues which creates the solid state-like tertiary structu ...
, by among other things, distances measured by NMR. Amino acids widely separated in a protein's
sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...
may touch or lie very close to one another within a stably folded protein. In a molten globule, on the other hand, their time-averaged distances are liable to be greater.
Learning ''how'' native state proteins can be manufactured is important, as attempts to create proteins from scratch have resulted in molten globules and not true native state products. Therefore, an understanding of the native state is crucial in
protein engineering
Protein engineering is the process of developing useful or valuable proteins. It is a young discipline, with much research taking place into the understanding of protein folding and recognition for protein design principles. It has been used to imp ...
.
Nucleic acids
Nucleic acids attain their native state through
base pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...
ing and, to a lesser extent, other interactions such as
coaxial stacking. Biological
DNA usually exists as long linear
double helices bound to proteins in
chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in r ...
, and biological
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
such as
tRNA
Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino ac ...
often form complex native configurations approaching the complexity of folded proteins. Additionally, artificial nucleic acid structures used in
DNA nanotechnology
DNA nanotechnology is the design and manufacture of artificial nucleic acid structures for technological uses. In this field, nucleic acids are used as non-biological engineering materials for nanotechnology rather than as the carriers of geneti ...
are designed to have specific native configurations in which multiple nucleic acid strands are assembled into a single complex.
In some cases native state of biological DNA performs their functions without being controlled by any other regulatory units.
External links
http://www.englandlab.com/protein-folding.html
{{DEFAULTSORT:Native State
Protein structure