What are Polypeptides?

Advertisements
Advertisements

Related Posts:


Making a polypeptide chain. Peptide bonds are formed by dehydration reactions, which link the carboxyl group of one amino acid to the amino group of the next. The peptide bonds are formed one at a time, starting with the amino acid at the amino end (N-terminus). The polypeptide has a repetitive backbone (purple) to which the amino acid side chains (yellow and green) are attached.
Source: Urry, Lisa A.. Campbell Biology (p. 78). Pearson Education. Kindle Edition.

What are Polypeptides? (Campbell Biology)

When two amino acids are positioned so that the carboxyl group of one is adjacent to the amino group of the other, they can become joined by a dehydration reaction, with the removal of a water molecule. The resulting covalent bond is called a peptide bond. Repeated over and over, this process yields a polypeptide, a polymer of many amino acids linked by peptide bonds.

The repeating sequence of atoms is called the polypeptide backbone. Extending from this backbone are the different side chains (R groups) of the amino acids. Polypeptides range in length from a few amino acids to 1,000 or more. Each specific polypeptide has a unique linear sequence of amino acids. Note that one end of the polypeptide chain has a free amino group (the N-terminus of the polypeptide), while the opposite end has a free carboxyl group (the C-terminus). The chemical nature of the molecule as a whole is determined by the kind and sequence of the side chains, which determine how a polypeptide folds and thus its final shape and chemical characteristics. The immense variety of polypeptides in nature illustrates an important concept introduced earlier—that cells can make many different polymers by linking a limited set of monomers into diverse sequences.


Source:

Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html

Advertisements
Advertisements

Related Research

Research Article: Rapid chain tracing of polypeptide backbones in electron-density maps

Date Published: March 01, 2010 Publisher: International Union of Crystallography Author(s): Thomas C. Terwilliger. http://doi.org/10.1107/S0907444910000272 Abstract: A method for rapid chain tracing of polypeptide backbones at moderate resolution is presented. Partial Text A key step in the determination of the structure of a macromolecule by X-ray crystallography is the interpretation of the electron density in … Continue reading

Research Article: Molecular Self-Assembly Strategy for Generating Catalytic Hybrid Polypeptides

Date Published: April 26, 2016 Publisher: Public Library of Science Author(s): Yoshiaki Maeda, Justin Fang, Yasuhiro Ikezoe, Douglas H. Pike, Vikas Nanda, Hiroshi Matsui, Bing Xu. http://doi.org/10.1371/journal.pone.0153700 Abstract: Recently, catalytic peptides were introduced that mimicked protease activities and showed promising selectivity of products even in organic solvents where protease cannot perform well. However, their catalytic … Continue reading

Research Article: Purification of Messenger Ribonucleoprotein Particles via a Tagged Nascent Polypeptide

Date Published: January 25, 2016 Publisher: Public Library of Science Author(s): Diana P. Inchaustegui Gil, Christine Clayton, Alexander F. Palazzo. http://doi.org/10.1371/journal.pone.0148131 Abstract: The cytoplasmic fates of mRNAs are influenced by interactions between RNA-binding proteins and cis regulatory motifs. In the cytoplasm, mRNAs are present as messenger ribonucleoprotein particles, which include not only proteins that bind … Continue reading

Research Article: Identification of Human Islet Amyloid Polypeptide as a BACE2 Substrate

Date Published: February 3, 2016 Publisher: Public Library of Science Author(s): Ingrid C. Rulifson, Ping Cao, Li Miao, David Kopecky, Linda Huang, Ryan D. White, Kim Samayoa, Jonitha Gardner, Xiaosu Wu, Kui Chen, Trace Tsuruda, Oliver Homann, Helene Baribault, Harvey Yamane, Tim Carlson, Jed Wiltzius, Yang Li, Massimo Pietropaolo. http://doi.org/10.1371/journal.pone.0147254 Abstract: Pancreatic amyloid formation by … Continue reading

Research Article: Functional Dissection of the Nascent Polypeptide-Associated Complex in Saccharomyces cerevisiae

Date Published: November 30, 2015 Publisher: Public Library of Science Author(s): Ann-Kathrin Ott, Lisa Locher, Miriam Koch, Elke Deuerling, Jeffrey L Brodsky. http://doi.org/10.1371/journal.pone.0143457 Abstract: Both the yeast nascent polypeptide-associated complex (NAC) and the Hsp40/70-based chaperone system RAC-Ssb are systems tethered to the ribosome to assist cotranslational processes such as folding of nascent polypeptides. While loss … Continue reading