Primary Structure of Protein (OpenStax Biology 2e)
Amino acids’ unique sequence in a polypeptide chain is its primary structure. For example, the pancreatic hormone insulin has two polypeptide chains, A and B, and they are linked together by disulfide bonds. The N terminal amino acid of the A chain is glycine; whereas, the C terminal amino acid is asparagine. The amino acid sequences in the A and B chains are unique to insulin.
The gene encoding the protein ultimately determines the unique sequence for every protein. A change in nucleotide sequence of the gene’s coding region may lead to adding a different amino acid to the growing polypeptide chain, causing a change in protein structure and function. In sickle cell anemia, the hemoglobin β chain has a single amino acid substitution, causing a change in protein structure and function. Specifically, valine in the β chain substitutes the amino acid glutamic. What is most remarkable to consider is that a hemoglobin molecule is comprised of two alpha and two beta chains that each consist of about 150 amino acids. The molecule, therefore, has about 600 amino acids. The structural difference between a normal hemoglobin molecule and a sickle cell molecule—which dramatically decreases life expectancy—is a single amino acid of the 600. What is even more remarkable is that three nucleotides each encode those 600 amino acids, and a single base change (point mutation), 1 in 1800 bases causes the mutation.– What type of amino acid sequence does protein primary structure have?
Because of this change of one amino acid in the chain, hemoglobin molecules form long fibers that distort the biconcave, or disc-shaped, red blood cells and causes them to assume a crescent or “sickle” shape, which clogs blood vessels. This can lead to myriad serious health problems such as breathlessness, dizziness, headaches, and abdominal pain for those affected by this disease.– What forms between thiol groups in two cysteine residues that are important component of the secondary and tertiary structure of proteins?
Peptides can be synthesised chemically via a range of laboratory methods. Chemical methods typically synthesise peptides in the opposite order (starting at the C-terminus) to biological protein synthesis (starting at the N-terminus).
Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e
Date Published: October 14, 2014 Publisher: Public Library of Science Author(s): Qiwei Li, David B. Dahl, Marina Vannucci, Jerry W. Tsai, Yang Zhang. http://doi.org/10.1371/journal.pone.0109832 Abstract: Determining the primary structure (i.e., amino acid sequence) of a protein has become cheaper, faster, and more accurate. Higher order protein structure provides insight into a protein’s function in the … Continue reading
Research Article: An Ensemble Method for Predicting Subnuclear Localizations from Primary Protein Structures
Date Published: February 27, 2013 Publisher: Public Library of Science Author(s): Guo Sheng Han, Zu Guo Yu, Vo Anh, Anaththa P. D. Krishnajith, Yu-Chu Tian, Lukasz Kurgan. http://doi.org/10.1371/journal.pone.0057225 Abstract: Predicting protein subnuclear localization is a challenging problem. Some previous works based on non-sequence information including Gene Ontology annotations and kernel fusion have respective limitations. The aim … Continue reading
Research Article: Aptamers as a Sensitive Tool to Detect Subtle Modifications in Therapeutic Proteins
Date Published: February 27, 2012 Publisher: Public Library of Science Author(s): Ran Zichel, Wanida Chearwae, Gouri Shankar Pandey, Basil Golding, Zuben E. Sauna, John J. Rossi. http://doi.org/10.1371/journal.pone.0031948 Abstract: Therapeutic proteins are derived from complex expression/production systems, which can result in minor conformational changes due to preferential codon usage in different organisms, post-translational modifications, etc. Subtle conformational … Continue reading
Date Published: August 7, 2009 Publisher: Public Library of Science Author(s): Oleksii Kuchaiev, Marija Rašajski, Desmond J. Higham, Nataša Pržulj, Teresa Maria Przytycka Abstract: Understanding complex networks of protein-protein interactions (PPIs) is one of the foremost challenges of the post-genomic era. Due to the recent advances in experimental bio-technology, including yeast-2-hybrid (Y2H), tandem affinity purification … Continue reading
Research Article: Prediction of Thermostability from Amino Acid Attributes by Combination of Clustering with Attribute Weighting: A New Vista in Engineering Enzymes
Date Published: August 10, 2011 Publisher: Public Library of Science Author(s): Mansour Ebrahimi, Amir Lakizadeh, Parisa Agha-Golzadeh, Esmaeil Ebrahimie, Mahdi Ebrahimi, Indra Neil Sarkar. http://doi.org/10.1371/journal.pone.0023146 Abstract: The engineering of thermostable enzymes is receiving increased attention. The paper, detergent, and biofuel industries, in particular, seek to use environmentally friendly enzymes instead of toxic chlorine chemicals. Enzymes typically … Continue reading